v4.1.0: DMS email documents, category-specific Nachweis linking, version system

- Save cover email body as DMS document with new 'email' context type
- Show email body separately from attachments in email detail view
- Add per-category DMS document assignment in quarterly confirmation
  (Studiennachweis, Einkommenssituation, Vermögenssituation)
- Add VERSION file and context processor for automatic version display
- Add MCP server, agent system, import/export, and new migrations
- Update compose files and production environment template

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/stiftung/agent/admin.py

@@ -0,0 +1,64 @@
+"""
+Django Admin für den AI Agent.
+
+Erreichbar unter /administration/agent/
+"""
+from django.contrib import admin
+from django.utils.html import format_html
+
+from .models import AgentConfig, ChatSession, ChatMessage
+
+
+@admin.register(AgentConfig)
+class AgentConfigAdmin(admin.ModelAdmin):
+    fieldsets = (
+        ("Provider", {
+            "fields": ("provider", "model_name", "ollama_url"),
+        }),
+        ("API-Keys (externe Provider)", {
+            "fields": ("openai_api_key", "anthropic_api_key"),
+            "classes": ("collapse",),
+            "description": "Nur ausfüllen wenn nicht Ollama verwendet wird.",
+        }),
+        ("Verhalten", {
+            "fields": ("system_prompt", "allow_write", "chat_retention_days"),
+        }),
+    )
+
+    def has_add_permission(self, request):
+        # Singleton: Hinzufügen nur wenn noch keine Config existiert
+        return not AgentConfig.objects.exists()
+
+    def has_delete_permission(self, request, obj=None):
+        return False
+
+
+class ChatMessageInline(admin.TabularInline):
+    model = ChatMessage
+    fields = ("role", "content_preview", "tool_name", "created_at")
+    readonly_fields = ("role", "content_preview", "tool_name", "created_at")
+    extra = 0
+    can_delete = False
+    ordering = ["created_at"]
+
+    def content_preview(self, obj):
+        return obj.content[:120] + ("…" if len(obj.content) > 120 else "")
+    content_preview.short_description = "Inhalt"
+
+
+@admin.register(ChatSession)
+class ChatSessionAdmin(admin.ModelAdmin):
+    list_display = ("title_or_id", "user", "message_count", "created_at", "updated_at")
+    list_filter = ("user",)
+    search_fields = ("title", "user__username")
+    readonly_fields = ("id", "user", "created_at", "updated_at")
+    inlines = [ChatMessageInline]
+    ordering = ["-updated_at"]
+
+    def title_or_id(self, obj):
+        return obj.title or str(obj.id)[:12]
+    title_or_id.short_description = "Sitzung"
+
+    def message_count(self, obj):
+        return obj.messages.count()
+    message_count.short_description = "Nachrichten"