feat: document templates with auto-fill from case data (P1)

- Database: kanzlai.document_templates table with RLS policies
- Seed: 4 system templates (Klageerwiderung UPC, Berufungsschrift,
  Mandatsbestätigung, Kostenrechnung)
- Backend: TemplateService (CRUD + render), TemplateHandler with
  endpoints: GET/POST /api/templates, GET/PUT/DELETE /api/templates/{id},
  POST /api/templates/{id}/render?case_id=X
- Template variables: case.*, party.*, tenant.*, user.*, date.*, deadline.*
- Frontend: /vorlagen page with category filters, template detail/editor,
  render flow (select case -> preview -> copy/download), variable toolbar
- Quick action: "Schriftsatz erstellen" button on case detail page
- Also: resolved merge conflicts between audit-trail and role-based branches,
  added missing Notification/AuditLog types to frontend

frontend/src/app/(app)/cases/[id]/layout.tsx

@@ -17,6 +17,7 @@ import {
   StickyNote,
   AlertTriangle,
   ScrollText,
+  FilePlus,
 } from "lucide-react";
 import { format } from "date-fns";
 import { de } from "date-fns/locale";
@@ -171,19 +172,28 @@ export default function CaseDetailLayout({
             {caseDetail.court_ref && <span>({caseDetail.court_ref})</span>}
           </div>
         </div>
-        <div className="text-right text-xs text-neutral-400">
-          <p>
-            Erstellt:{" "}
-            {format(new Date(caseDetail.created_at), "d. MMM yyyy", {
-              locale: de,
-            })}
-          </p>
-          <p>
-            Aktualisiert:{" "}
-            {format(new Date(caseDetail.updated_at), "d. MMM yyyy", {
-              locale: de,
-            })}
-          </p>
+        <div className="flex flex-col items-end gap-2">
+          <Link
+            href={`/vorlagen?case_id=${id}`}
+            className="flex items-center gap-1.5 rounded-md bg-neutral-900 px-3 py-1.5 text-sm font-medium text-white transition-colors hover:bg-neutral-800"
+          >
+            <FilePlus className="h-3.5 w-3.5" />
+            Schriftsatz erstellen
+          </Link>
+          <div className="text-right text-xs text-neutral-400">
+            <p>
+              Erstellt:{" "}
+              {format(new Date(caseDetail.created_at), "d. MMM yyyy", {
+                locale: de,
+              })}
+            </p>
+            <p>
+              Aktualisiert:{" "}
+              {format(new Date(caseDetail.updated_at), "d. MMM yyyy", {
+                locale: de,
+              })}
+            </p>
+          </div>
         </div>
       </div>
 

frontend/src/app/(app)/vorlagen/[id]/page.tsx

@@ -0,0 +1,174 @@
+"use client";
+
+import { useQuery, useMutation, useQueryClient } from "@tanstack/react-query";
+import { useParams, useRouter } from "next/navigation";
+import { api } from "@/lib/api";
+import type { DocumentTemplate } from "@/lib/types";
+import { TEMPLATE_CATEGORY_LABELS } from "@/lib/types";
+import { Breadcrumb } from "@/components/layout/Breadcrumb";
+import { TemplateEditor } from "@/components/templates/TemplateEditor";
+import Link from "next/link";
+import {
+  Loader2,
+  Lock,
+  Trash2,
+  FileDown,
+  ArrowRight,
+} from "lucide-react";
+import { toast } from "sonner";
+import { useState } from "react";
+
+export default function TemplateDetailPage() {
+  const { id } = useParams<{ id: string }>();
+  const router = useRouter();
+  const queryClient = useQueryClient();
+  const [isEditing, setIsEditing] = useState(false);
+
+  const { data: template, isLoading } = useQuery({
+    queryKey: ["template", id],
+    queryFn: () => api.get<DocumentTemplate>(`/templates/${id}`),
+  });
+
+  const deleteMutation = useMutation({
+    mutationFn: () => api.delete(`/templates/${id}`),
+    onSuccess: () => {
+      queryClient.invalidateQueries({ queryKey: ["templates"] });
+      toast.success("Vorlage gelöscht");
+      router.push("/vorlagen");
+    },
+    onError: () => toast.error("Fehler beim Löschen"),
+  });
+
+  const updateMutation = useMutation({
+    mutationFn: (data: Partial<DocumentTemplate>) =>
+      api.put<DocumentTemplate>(`/templates/${id}`, data),
+    onSuccess: () => {
+      queryClient.invalidateQueries({ queryKey: ["template", id] });
+      queryClient.invalidateQueries({ queryKey: ["templates"] });
+      toast.success("Vorlage gespeichert");
+      setIsEditing(false);
+    },
+    onError: () => toast.error("Fehler beim Speichern"),
+  });
+
+  if (isLoading) {
+    return (
+      <div className="flex items-center justify-center py-12">
+        <Loader2 className="h-5 w-5 animate-spin text-neutral-400" />
+      </div>
+    );
+  }
+
+  if (!template) {
+    return (
+      <div className="py-12 text-center text-sm text-neutral-500">
+        Vorlage nicht gefunden
+      </div>
+    );
+  }
+
+  return (
+    <div className="animate-fade-in space-y-4">
+      <Breadcrumb
+        items={[
+          { label: "Dashboard", href: "/dashboard" },
+          { label: "Vorlagen", href: "/vorlagen" },
+          { label: template.name },
+        ]}
+      />
+
+      <div className="flex flex-col gap-3 sm:flex-row sm:items-center sm:justify-between">
+        <div>
+          <div className="flex items-center gap-2">
+            <h1 className="text-lg font-semibold text-neutral-900">
+              {template.name}
+            </h1>
+            {template.is_system && (
+              <Lock className="h-4 w-4 text-neutral-400" aria-label="Systemvorlage" />
+            )}
+          </div>
+          <div className="mt-1 flex items-center gap-2">
+            <span className="rounded-full bg-neutral-100 px-2 py-0.5 text-xs text-neutral-600">
+              {TEMPLATE_CATEGORY_LABELS[template.category] ?? template.category}
+            </span>
+            {template.description && (
+              <span className="text-xs text-neutral-500">
+                {template.description}
+              </span>
+            )}
+          </div>
+        </div>
+
+        <div className="flex items-center gap-2">
+          <Link
+            href={`/vorlagen/${id}/render`}
+            className="flex items-center gap-1.5 rounded-md bg-neutral-900 px-3 py-1.5 text-sm font-medium text-white transition-colors hover:bg-neutral-800"
+          >
+            <FileDown className="h-3.5 w-3.5" />
+            Dokument erstellen
+            <ArrowRight className="h-3.5 w-3.5" />
+          </Link>
+          {!template.is_system && (
+            <>
+              <button
+                onClick={() => setIsEditing(!isEditing)}
+                className="rounded-md border border-neutral-200 bg-white px-3 py-1.5 text-sm text-neutral-700 transition-colors hover:bg-neutral-50"
+              >
+                {isEditing ? "Abbrechen" : "Bearbeiten"}
+              </button>
+              <button
+                onClick={() => {
+                  if (confirm("Vorlage wirklich löschen?")) {
+                    deleteMutation.mutate();
+                  }
+                }}
+                className="rounded-md border border-red-200 bg-white p-1.5 text-red-600 transition-colors hover:bg-red-50"
+              >
+                <Trash2 className="h-4 w-4" />
+              </button>
+            </>
+          )}
+        </div>
+      </div>
+
+      {isEditing ? (
+        <TemplateEditor
+          template={template}
+          onSave={(data) => updateMutation.mutate(data)}
+          isSaving={updateMutation.isPending}
+        />
+      ) : (
+        <div className="space-y-4">
+          {/* Variables */}
+          {template.variables && template.variables.length > 0 && (
+            <div className="rounded-lg border border-neutral-200 bg-white p-4">
+              <h3 className="mb-2 text-sm font-medium text-neutral-700">
+                Variablen
+              </h3>
+              <div className="flex flex-wrap gap-1.5">
+                {template.variables.map((v: string) => (
+                  <code
+                    key={v}
+                    className="rounded bg-neutral-100 px-1.5 py-0.5 text-xs text-neutral-600"
+                  >
+                    {`{{${v}}}`}
+                  </code>
+                ))}
+              </div>
+            </div>
+          )}
+
+          {/* Content preview */}
+          <div className="rounded-lg border border-neutral-200 bg-white p-6">
+            <h3 className="mb-3 text-sm font-medium text-neutral-700">
+              Vorschau
+            </h3>
+            <div className="prose prose-sm prose-neutral max-w-none whitespace-pre-wrap font-mono text-xs leading-relaxed text-neutral-700">
+              {template.content}
+            </div>
+          </div>
+        </div>
+      )}
+    </div>
+  );
+}

frontend/src/app/(app)/vorlagen/[id]/render/page.tsx

@@ -0,0 +1,177 @@
+"use client";
+
+import { useQuery, useMutation } from "@tanstack/react-query";
+import { useParams } from "next/navigation";
+import { api } from "@/lib/api";
+import type { DocumentTemplate, Case, RenderResponse } from "@/lib/types";
+import { Breadcrumb } from "@/components/layout/Breadcrumb";
+import {
+  Loader2,
+  FileDown,
+  Copy,
+  Check,
+} from "lucide-react";
+import { useState } from "react";
+import { toast } from "sonner";
+
+export default function RenderTemplatePage() {
+  const { id } = useParams<{ id: string }>();
+  const [selectedCaseId, setSelectedCaseId] = useState("");
+  const [rendered, setRendered] = useState<RenderResponse | null>(null);
+  const [copied, setCopied] = useState(false);
+
+  const { data: template, isLoading: templateLoading } = useQuery({
+    queryKey: ["template", id],
+    queryFn: () => api.get<DocumentTemplate>(`/templates/${id}`),
+  });
+
+  const { data: casesData, isLoading: casesLoading } = useQuery({
+    queryKey: ["cases"],
+    queryFn: () =>
+      api.get<{ data: Case[]; total: number }>("/cases?limit=100"),
+  });
+
+  const cases = casesData?.data ?? [];
+
+  const renderMutation = useMutation({
+    mutationFn: () =>
+      api.post<RenderResponse>(
+        `/templates/${id}/render${selectedCaseId ? `?case_id=${selectedCaseId}` : ""}`,
+      ),
+    onSuccess: (data) => setRendered(data),
+    onError: () => toast.error("Fehler beim Erstellen"),
+  });
+
+  const handleCopy = async () => {
+    if (!rendered) return;
+    await navigator.clipboard.writeText(rendered.content);
+    setCopied(true);
+    toast.success("In Zwischenablage kopiert");
+    setTimeout(() => setCopied(false), 2000);
+  };
+
+  const handleDownload = () => {
+    if (!rendered) return;
+    const blob = new Blob([rendered.content], { type: "text/markdown" });
+    const url = URL.createObjectURL(blob);
+    const a = document.createElement("a");
+    a.href = url;
+    a.download = `${rendered.name.replace(/\s+/g, "_")}.md`;
+    a.click();
+    URL.revokeObjectURL(url);
+    toast.success("Dokument heruntergeladen");
+  };
+
+  if (templateLoading) {
+    return (
+      <div className="flex items-center justify-center py-12">
+        <Loader2 className="h-5 w-5 animate-spin text-neutral-400" />
+      </div>
+    );
+  }
+
+  if (!template) {
+    return (
+      <div className="py-12 text-center text-sm text-neutral-500">
+        Vorlage nicht gefunden
+      </div>
+    );
+  }
+
+  return (
+    <div className="animate-fade-in space-y-4">
+      <Breadcrumb
+        items={[
+          { label: "Dashboard", href: "/dashboard" },
+          { label: "Vorlagen", href: "/vorlagen" },
+          { label: template.name, href: `/vorlagen/${id}` },
+          { label: "Dokument erstellen" },
+        ]}
+      />
+
+      <h1 className="text-lg font-semibold text-neutral-900">
+        Dokument erstellen
+      </h1>
+      <p className="text-sm text-neutral-500">
+        Vorlage &ldquo;{template.name}&rdquo; mit Falldaten befüllen
+      </p>
+
+      {/* Step 1: Select case */}
+      <div className="rounded-lg border border-neutral-200 bg-white p-4">
+        <h3 className="mb-3 text-sm font-medium text-neutral-700">
+          1. Akte auswählen
+        </h3>
+        {casesLoading ? (
+          <Loader2 className="h-4 w-4 animate-spin text-neutral-400" />
+        ) : (
+          <select
+            value={selectedCaseId}
+            onChange={(e) => {
+              setSelectedCaseId(e.target.value);
+              setRendered(null);
+            }}
+            className="w-full rounded-md border border-neutral-200 px-3 py-2 text-sm text-neutral-700 focus:border-neutral-400 focus:outline-none"
+          >
+            <option value="">Ohne Akte (nur Datumsvariablen)</option>
+            {cases.map((c) => (
+              <option key={c.id} value={c.id}>
+                {c.case_number} — {c.title}
+              </option>
+            ))}
+          </select>
+        )}
+      </div>
+
+      {/* Step 2: Render */}
+      <div className="rounded-lg border border-neutral-200 bg-white p-4">
+        <div className="flex items-center justify-between">
+          <h3 className="text-sm font-medium text-neutral-700">
+            2. Vorschau erstellen
+          </h3>
+          <button
+            onClick={() => renderMutation.mutate()}
+            disabled={renderMutation.isPending}
+            className="flex items-center gap-1.5 rounded-md bg-neutral-900 px-3 py-1.5 text-sm font-medium text-white transition-colors hover:bg-neutral-800 disabled:opacity-50"
+          >
+            {renderMutation.isPending ? (
+              <Loader2 className="h-3.5 w-3.5 animate-spin" />
+            ) : (
+              <FileDown className="h-3.5 w-3.5" />
+            )}
+            Vorschau
+          </button>
+        </div>
+
+        {rendered && (
+          <div className="mt-4">
+            <div className="mb-2 flex items-center justify-end gap-2">
+              <button
+                onClick={handleCopy}
+                className="flex items-center gap-1 rounded-md border border-neutral-200 px-2.5 py-1 text-xs text-neutral-600 transition-colors hover:bg-neutral-50"
+              >
+                {copied ? (
+                  <Check className="h-3 w-3" />
+                ) : (
+                  <Copy className="h-3 w-3" />
+                )}
+                {copied ? "Kopiert" : "Kopieren"}
+              </button>
+              <button
+                onClick={handleDownload}
+                className="flex items-center gap-1 rounded-md border border-neutral-200 px-2.5 py-1 text-xs text-neutral-600 transition-colors hover:bg-neutral-50"
+              >
+                <FileDown className="h-3 w-3" />
+                Herunterladen
+              </button>
+            </div>
+            <div className="rounded-lg border border-neutral-200 bg-neutral-50 p-6">
+              <div className="whitespace-pre-wrap font-mono text-xs leading-relaxed text-neutral-700">
+                {rendered.content}
+              </div>
+            </div>
+          </div>
+        )}
+      </div>
+    </div>
+  );
+}

frontend/src/app/(app)/vorlagen/neu/page.tsx

@@ -0,0 +1,46 @@
+"use client";
+
+import { useMutation, useQueryClient } from "@tanstack/react-query";
+import { useRouter } from "next/navigation";
+import { api } from "@/lib/api";
+import type { DocumentTemplate } from "@/lib/types";
+import { Breadcrumb } from "@/components/layout/Breadcrumb";
+import { TemplateEditor } from "@/components/templates/TemplateEditor";
+import { toast } from "sonner";
+
+export default function NeueVorlagePage() {
+  const router = useRouter();
+  const queryClient = useQueryClient();
+
+  const createMutation = useMutation({
+    mutationFn: (data: Partial<DocumentTemplate>) =>
+      api.post<DocumentTemplate>("/templates", data),
+    onSuccess: (result) => {
+      queryClient.invalidateQueries({ queryKey: ["templates"] });
+      toast.success("Vorlage erstellt");
+      router.push(`/vorlagen/${result.id}`);
+    },
+    onError: () => toast.error("Fehler beim Erstellen"),
+  });
+
+  return (
+    <div className="animate-fade-in space-y-4">
+      <Breadcrumb
+        items={[
+          { label: "Dashboard", href: "/dashboard" },
+          { label: "Vorlagen", href: "/vorlagen" },
+          { label: "Neue Vorlage" },
+        ]}
+      />
+
+      <h1 className="text-lg font-semibold text-neutral-900">
+        Neue Vorlage erstellen
+      </h1>
+
+      <TemplateEditor
+        onSave={(data) => createMutation.mutate(data)}
+        isSaving={createMutation.isPending}
+      />
+    </div>
+  );
+}

frontend/src/app/(app)/vorlagen/page.tsx

@@ -0,0 +1,121 @@
+"use client";
+
+import { useQuery } from "@tanstack/react-query";
+import { api } from "@/lib/api";
+import type { DocumentTemplate } from "@/lib/types";
+import { TEMPLATE_CATEGORY_LABELS } from "@/lib/types";
+import { Breadcrumb } from "@/components/layout/Breadcrumb";
+import Link from "next/link";
+import { FileText, Plus, Loader2, Lock } from "lucide-react";
+import { useState } from "react";
+
+const CATEGORIES = ["", "schriftsatz", "vertrag", "korrespondenz", "intern"];
+
+export default function VorlagenPage() {
+  const [category, setCategory] = useState("");
+
+  const { data, isLoading } = useQuery({
+    queryKey: ["templates", category],
+    queryFn: () =>
+      api.get<{ data: DocumentTemplate[]; total: number }>(
+        `/templates${category ? `?category=${category}` : ""}`,
+      ),
+  });
+
+  const templates = data?.data ?? [];
+
+  return (
+    <div className="animate-fade-in space-y-4">
+      <div>
+        <Breadcrumb
+          items={[
+            { label: "Dashboard", href: "/dashboard" },
+            { label: "Vorlagen" },
+          ]}
+        />
+        <div className="flex flex-col gap-3 sm:flex-row sm:items-center sm:justify-between">
+          <div>
+            <h1 className="text-lg font-semibold text-neutral-900">
+              Vorlagen
+            </h1>
+            <p className="mt-0.5 text-sm text-neutral-500">
+              Dokumentvorlagen mit automatischer Befüllung
+            </p>
+          </div>
+          <Link
+            href="/vorlagen/neu"
+            className="flex items-center gap-1.5 rounded-md bg-neutral-900 px-3 py-1.5 text-sm font-medium text-white transition-colors hover:bg-neutral-800"
+          >
+            <Plus className="h-3.5 w-3.5" />
+            Neue Vorlage
+          </Link>
+        </div>
+      </div>
+
+      {/* Category filter */}
+      <div className="flex gap-1.5 overflow-x-auto">
+        {CATEGORIES.map((cat) => (
+          <button
+            key={cat}
+            onClick={() => setCategory(cat)}
+            className={`whitespace-nowrap rounded-md px-3 py-1.5 text-sm transition-colors ${
+              category === cat
+                ? "bg-neutral-900 font-medium text-white"
+                : "bg-white text-neutral-600 ring-1 ring-neutral-200 hover:bg-neutral-50"
+            }`}
+          >
+            {cat === "" ? "Alle" : TEMPLATE_CATEGORY_LABELS[cat] ?? cat}
+          </button>
+        ))}
+      </div>
+
+      {isLoading ? (
+        <div className="flex items-center justify-center py-12">
+          <Loader2 className="h-5 w-5 animate-spin text-neutral-400" />
+        </div>
+      ) : templates.length === 0 ? (
+        <div className="flex flex-col items-center justify-center rounded-lg border border-dashed border-neutral-300 py-12 text-center">
+          <FileText className="mb-2 h-8 w-8 text-neutral-300" />
+          <p className="text-sm text-neutral-500">Keine Vorlagen gefunden</p>
+        </div>
+      ) : (
+        <div className="grid gap-3 sm:grid-cols-2 lg:grid-cols-3">
+          {templates.map((t) => (
+            <Link
+              key={t.id}
+              href={`/vorlagen/${t.id}`}
+              className="group rounded-lg border border-neutral-200 bg-white p-4 transition-colors hover:border-neutral-300 hover:shadow-sm"
+            >
+              <div className="flex items-start justify-between">
+                <div className="flex items-center gap-2">
+                  <FileText className="h-4 w-4 text-neutral-400" />
+                  <h3 className="text-sm font-medium text-neutral-900 group-hover:text-neutral-700">
+                    {t.name}
+                  </h3>
+                </div>
+                {t.is_system && (
+                  <Lock className="h-3.5 w-3.5 text-neutral-300" aria-label="Systemvorlage" />
+                )}
+              </div>
+              {t.description && (
+                <p className="mt-1.5 text-xs text-neutral-500 line-clamp-2">
+                  {t.description}
+                </p>
+              )}
+              <div className="mt-3 flex items-center gap-2">
+                <span className="rounded-full bg-neutral-100 px-2 py-0.5 text-xs text-neutral-600">
+                  {TEMPLATE_CATEGORY_LABELS[t.category] ?? t.category}
+                </span>
+                {t.is_system && (
+                  <span className="rounded-full bg-blue-50 px-2 py-0.5 text-xs text-blue-600">
+                    System
+                  </span>
+                )}
+              </div>
+            </Link>
+          ))}
+        </div>
+      )}
+    </div>
+  );
+}