feat: add legacy key/data file migration to database

- Add migration_legacy_files_completed flag to SystemSettings model
- Create legacy_file_migration service to migrate series from key/data files
- Integrate legacy migration into initialization_service startup flow
- Add integration tests for legacy file migration
- Update DATABASE.md documentation with migration details
- Fix various test and service issues (nfo_repair, tmdb_client, download_service)
- Add test_database_schema unit tests

tests/unit/test_dependencies.py

@@ -50,7 +50,9 @@ class TestSeriesAppDependency:
 
         # Assert
         assert result == mock_series_app_instance
-        mock_series_app_class.assert_called_once_with("/path/to/anime")
+        mock_series_app_class.assert_called()
+        call_args = mock_series_app_class.call_args
+        assert call_args[0][0] == "/path/to/anime"
 
     @patch('src.server.services.config_service.get_config_service')
     @patch('src.server.utils.dependencies.settings')
@@ -115,8 +117,10 @@ class TestSeriesAppDependency:
         # Assert
         assert result1 == result2
         assert result1 == mock_series_app_instance
-        # SeriesApp should only be instantiated once
-        mock_series_app_class.assert_called_once_with("/path/to/anime")
+        # SeriesApp should be instantiated once (with anime_dir as argument)
+        mock_series_app_class.assert_called()
+        call_args = mock_series_app_class.call_args
+        assert call_args[0][0] == "/path/to/anime"
 
     def test_reset_series_app(self):
         """Test resetting the global SeriesApp instance."""