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/plugin.py

@@ -193,8 +193,8 @@ class AutomationPlugin(BasePlugin):
             logger.exception("Failed to register agent coordinator tools")
         # Register MiniApps from manifest
         try:
-            from app.plugins.builtins.kommunikation.contracts import MiniAppRegistry
-            registry = MiniAppRegistry()
+            from app.plugins.builtins.kommunikation.contracts import get_miniapp_registry
+            registry = get_miniapp_registry()
             for miniapp in self.manifest.miniapps:
                 registry.register(
                     app_id=miniapp.app_id,
@@ -236,8 +236,8 @@ class AutomationPlugin(BasePlugin):
             logger.exception("Failed to unregister agent coordinator tools")
         # Unregister MiniApps
         try:
-            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_plugin(self.manifest.name)
             logger.info("Unregistered MiniApps for plugin '%s'", self.manifest.name)
         except Exception: