feat: Phase B — interactive dashboard, breadcrumbs, clickable navigation

- Breadcrumb component: reusable nav with items array (label+href)
- DeadlineTrafficLights: buttons → Links to /fristen?status={filter}
- CaseOverviewGrid: static metrics → clickable Links to /cases?status={filter}
- UpcomingTimeline: items → clickable Links to /fristen/{id} or /termine/{id}
  with case number links and hover chevron
- QuickActions: swap CalDAV Sync for "Neuer Termin" → /termine/neu,
  fix "Frist eintragen" → /fristen/neu
- AISummaryCard: add RefreshCw button with spinning animation
- RecentActivityList: new component showing recent case events
- DeadlineList: accept initialStatus prop, add this_week/ok filters
- fristen/page.tsx: read searchParams.status for initial filter
- Add breadcrumbs to dashboard, fristen, cases, termine pages
- Add RecentActivity type, update DashboardData type

frontend/src/components/dashboard/AISummaryCard.tsx

@@ -1,10 +1,12 @@
 "use client";
 
-import { Sparkles } from "lucide-react";
+import { useState } from "react";
+import { Sparkles, RefreshCw } from "lucide-react";
 import type { DashboardData } from "@/lib/types";
 
 interface Props {
   data: DashboardData;
+  onRefresh?: () => void;
 }
 
 function generateSummary(data: DashboardData): string {
@@ -51,18 +53,39 @@ function generateSummary(data: DashboardData): string {
   return parts.join(" ");
 }
 
-export function AISummaryCard({ data }: Props) {
+export function AISummaryCard({ data, onRefresh }: Props) {
+  const [spinning, setSpinning] = useState(false);
   const summary = generateSummary(data);
 
+  function handleRefresh() {
+    if (!onRefresh) return;
+    setSpinning(true);
+    onRefresh();
+    setTimeout(() => setSpinning(false), 1000);
+  }
+
   return (
     <div className="rounded-xl border border-neutral-200 bg-white p-5">
-      <div className="flex items-center gap-2">
-        <div className="rounded-md bg-violet-50 p-1.5">
-          <Sparkles className="h-4 w-4 text-violet-500" />
+      <div className="flex items-center justify-between">
+        <div className="flex items-center gap-2">
+          <div className="rounded-md bg-violet-50 p-1.5">
+            <Sparkles className="h-4 w-4 text-violet-500" />
+          </div>
+          <h2 className="text-sm font-semibold text-neutral-900">
+            KI-Zusammenfassung
+          </h2>
         </div>
-        <h2 className="text-sm font-semibold text-neutral-900">
-          KI-Zusammenfassung
-        </h2>
+        {onRefresh && (
+          <button
+            onClick={handleRefresh}
+            title="Aktualisieren"
+            className="rounded-md p-1.5 text-neutral-400 transition-colors hover:bg-neutral-100 hover:text-neutral-600"
+          >
+            <RefreshCw
+              className={`h-4 w-4 ${spinning ? "animate-spin" : ""}`}
+            />
+          </button>
+        )}
       </div>
       <p className="mt-3 text-sm leading-relaxed text-neutral-700">
         {summary}