feat(B-PLUGIN-MINIAPP-WIRE): MiniApp Registry als Singleton — gemeinsame Registry für alle Plugins

B-PLUGIN-MINIAPP-WIRE: MiniAppRegistry Singleton-Pattern
- get_miniapp_registry() / reset_miniapp_registry() in miniapp_registry.py
- Alle 6 MiniAppRegistry() Instanziierungen durch get_miniapp_registry() ersetzt
- automation/plugin.py (on_activate/on_deactivate), automation/routes.py (3x), kommunikation/plugin.py
- contracts.py: get_miniapp_registry + reset_miniapp_registry exportiert
- 0 verbleibende MiniAppRegistry() Instanziierungen außerhalb miniapp_registry.py

Tests: 12 Tests in test_miniapp_registry.py — alle grün
- Singleton, Register/List, UnregisterPlugin, Plugin-Lifecycle-Integration

app/plugins/builtins/automation/routes.py

@@ -187,8 +187,8 @@ async def list_miniapps(
     current_user: dict[str, Any] = Depends(get_current_user),
 ):
     """List custom MiniApps from plugin config."""
-    from app.plugins.builtins.kommunikation.contracts import MiniAppRegistry
-    registry = MiniAppRegistry()
+    from app.plugins.builtins.kommunikation.contracts import get_miniapp_registry
+    registry = get_miniapp_registry()
     items = registry.list_apps()
     return {"items": items, "total": len(items)}
 
@@ -204,8 +204,8 @@ async def create_miniapp(
     current_user: dict[str, Any] = Depends(get_current_user),
 ):
     """Create a custom MiniApp definition."""
-    from app.plugins.builtins.kommunikation.contracts import MiniAppRegistry
-    registry = MiniAppRegistry()
+    from app.plugins.builtins.kommunikation.contracts import get_miniapp_registry
+    registry = get_miniapp_registry()
     registry.register(
         app_id=data.app_id,
         name=data.name,
@@ -233,8 +233,8 @@ async def delete_miniapp(
     current_user: dict[str, Any] = Depends(get_current_user),
 ):
     """Delete a custom MiniApp definition."""
-    from app.plugins.builtins.kommunikation.contracts import MiniAppRegistry
-    registry = MiniAppRegistry()
+    from app.plugins.builtins.kommunikation.contracts import get_miniapp_registry
+    registry = get_miniapp_registry()
     registry.unregister(app_id)
     return {"status": "ok"}