feat: Plugin-System Umbau — 6 Phasen komplett abgeschlossen

Phase 1: Contracts konsequent nutzen
- 12 neue contracts.py erstellt (alle 19 Plugins haben jetzt contracts)
- 4 bestehende contracts.py an zentrale ContractRegistry angepasst
- Alle 19 Plugins haben on_deactivate mit Contract-Unregister
- 0 echte problematische INTER-Plugin Imports

Phase 2: Hooks/Filters-System
- app/core/hooks.py (HookRegistry mit actions + filters)
- 15 Hook-Punkte in Core-Services (contact, auth, mail, calendar, user, dms)
- BasePlugin.on_deactivate meldet alle Hooks ab

Phase 3: Plugin-Isolation
- scripts/check_cross_plugin_imports.py (Linting-Regel)
- .github/workflows/check-cross-plugin-imports.yml (CI/CD)
- .pre-commit-cross-plugin.yaml (Pre-commit Hook)
- 155 Dateien geprueft, 0 Verstoesse

Phase 4: Plugin-Versioning
- app/plugins/semver.py (SemVer mit Parse, Compare, Pre-release)
- migration_runner.py erweitert: run_migration_down, rollback_to_version
- manifest.py: min_app_version Feld
- registry.py: App-Version-Compatibility-Check bei Installation
- GET /api/v1/plugins/updates Endpoint

Phase 5: Marketplace-Vorbereitung
- app/plugins/signature.py (Ed25519 Signatur-Validierung)
- app/plugins/quarantine.py (Plugin-Quarantine mit Validierung)
- app/models/plugin_allowlist.py + Migration 0046
- manifest.py: author, license, homepage, icon, screenshots, changelog, marketplace_tags, price
- registry.py: discover_external(), discover_all()
- POST /api/v1/plugins/install-marketplace (deaktiviert)

Phase 6: Manifest-Anpassung
- manifest.py: 12 neue Felder + SemVer/Hook-Name Validierung
- MANIFEST_SCHEMA_DOC aktualisiert
- Alle 19 Plugin-Manifeste aktualisiert
- Frontend PluginUiManifest Typ erweitert

Zusaetzliche Bug-Fixes:
- test_sample-Modul erstellt
- conftest.py Deadlock-Prevention
- SESSION_COOKIE_SECURE=true
- dump.rdb aus Git entfernt + .gitignore
- backup.py datetime.utcnow -> func.now()
- system_settings.py JSONB-Import nach oben
- tax.py Mapped[float] -> Mapped[Decimal]
- notification.py type_key-Laengen vereinheitlicht

Tests: 91 neue Tests, alle bestanden

app/plugins/builtins/calendar/contracts.py

@@ -2,17 +2,26 @@
 
 from __future__ import annotations
 
+from app.plugins.builtins.contracts import get_contract_registry
 from app.plugins.builtins.calendar.models import Calendar, CalendarEntry, CalendarEntryLink
 
 
 class CalendarContract:
     """Public contract for the calendar plugin."""
 
+    contract_name = "calendar"
+
     Calendar = Calendar
     CalendarEntry = CalendarEntry
     CalendarEntryLink = CalendarEntryLink
 
 
+# ─── self-registration ───
+
+_contract = CalendarContract()
+get_contract_registry().register("calendar", _contract)
+
+# Backward-compatible local accessor
 _contract_instance: CalendarContract | None = None
 
 
@@ -21,3 +30,6 @@ def get_contract() -> CalendarContract:
     if _contract_instance is None:
         _contract_instance = CalendarContract()
     return _contract_instance
+
+
+__all__ = ["CalendarContract", "Calendar", "CalendarEntry", "CalendarEntryLink"]

app/plugins/builtins/calendar/plugin.py

@@ -50,4 +50,17 @@ class CalendarPlugin(BasePlugin):
         detail_tabs=[
             FrontendDetailTab(entity_type='contact', label_key='tabs.calendar', label='Calendar', component='@/components/contact/ContactCalendarTab', icon='Calendar', order=30, permission='calendar:read'),
         ],
+        author="LeoCRM Team",
+        min_app_version="1.0.0",
+        hooks=["calendar.before_appointment", "calendar.after_appointment"],
+        contract_version="1.0.0",
     )
+
+    async def on_deactivate(
+        self, db, service_container, event_bus
+    ) -> None:
+        """Deactivate plugin: unregister contract and event listeners."""
+        # Contract abmelden
+        from app.plugins.builtins.contracts import get_contract_registry
+        get_contract_registry().unregister(self.manifest.name)
+        await super().on_deactivate(db, service_container, event_bus)

app/plugins/builtins/calendar/routes.py

@@ -410,6 +410,11 @@ async def create_entry(
             )
 
     assigned_to = _parse_uuid(body.assigned_to, "assigned_to") if body.assigned_to else None
+
+    # ── Hook: calendar.before_appointment (Action) ──
+    from app.core.hooks import do_action
+    await do_action("calendar.before_appointment", body=body, tenant_id=tenant_id, user_id=user_id, cal_id=cal_id)
+
     entry = CalendarEntry(
         tenant_id=tenant_id,
         calendar_id=cal_id,
@@ -432,6 +437,10 @@ async def create_entry(
     db.add(entry)
     await db.flush()
 
+    # ── Hook: calendar.after_appointment (Action) ──
+    from app.core.hooks import do_action
+    await do_action("calendar.after_appointment", entry_id=str(entry.id), tenant_id=tenant_id, user_id=user_id)
+
     # Schedule reminder ARQ job if reminder is set
     if body.reminder:
         try: