fix(types): resolve pre-existing basedpyright errors in tests

Fix ~790 basedpyright errors across the test suite:
- Type stub subclasses of real production classes with super().__init__()
- Add missing generic type arguments and Dict[str, Any] annotations
- Add None guards before subscript/member access
- Adapt tests to production API changes (removed dead handlers,
  PersistentModelCache.get_default, _i18n_filter_added location)

tests/services/test_example_images_cleanup_service.py

@@ -54,7 +54,7 @@ async def test_cleanup_moves_empty_and_orphaned(tmp_path, monkeypatch):
 
         result = await service.cleanup_example_image_folders()
 
-        deleted_bucket = Path(result['deleted_root'])
+        deleted_bucket = Path(str(result['deleted_root']))
         assert result['success'] is True
         assert result['moved_total'] == 2
         assert not empty_folder.exists()