This commit modifies the `process_faces` method in both the `PhotoTagger` and `FaceProcessor` classes to accept an optional `limit` parameter. If `None`, all unprocessed photos will be processed, enhancing flexibility in face processing. Additionally, the `get_unprocessed_photos` method in `DatabaseManager` is updated to handle the optional limit, ensuring consistent behavior across the application. Docstrings have been updated to reflect these changes, improving code documentation and clarity.