feat(5.22): Saved Searches / Smart Lists — reusable filters for list views

- SavedFilter model with TenantMixin (name, entity_type, filter_criteria JSONB, user_id)
- Routes: GET/POST /saved-filters, DELETE /saved-filters/{id} with RBAC
- Alembic migration 0029_saved_filters creates saved_filters table
- Frontend: SavedFilters.tsx component with save/load/delete UI
- Frontend: api/savedFilters.ts with React Query hooks
- Integrated into ContactsListPage as example
- i18n keys for savedFilters.* in de.json and en.json
- Tests: test_saved_filters.py (9 tests) + SavedFilters.test.tsx (3 tests)
- Registered SavedFilter in conftest.py

frontend/src/i18n/locales/de.json

@@ -1022,5 +1022,15 @@
     "priorityMedium": "Mittel",
     "priorityHigh": "Hoch",
     "priorityUrgent": "Dringend"
+  },
+  "savedFilters": {
+    "save": "Filter speichern",
+    "saveTitle": "Filter speichern",
+    "name": "Filtername",
+    "namePlaceholder": "z.B. Wichtige Kunden",
+    "saved": "Filter gespeichert",
+    "deleted": "Filter gelöscht",
+    "load": "Filter laden",
+    "noFilters": "Keine gespeicherten Filter"
   }
 }