feat: improve civitai data handling and type safety, fixes #565

- Replace setdefault with get and explicit dict initialization in MetadataUpdater
- Change civitai field type from Optional[Dict] to Dict[str, Any] with default_factory
- Add None check and dict initialization in BaseModelMetadata.__post_init__
- Ensures civitai data is always a dictionary, preventing type errors and improving code reliability

py/utils/example_images_metadata.py

@@ -270,7 +270,12 @@ class MetadataUpdater:
         """
         try:
             await MetadataManager.hydrate_model_data(model_data)
-            civitai_data = model_data.setdefault('civitai', {})
+            civitai_data = model_data.get('civitai')
+
+            if not isinstance(civitai_data, dict):
+                civitai_data = {}
+                model_data['civitai'] = civitai_data
+
             custom_images = civitai_data.get('customImages')
 
             if not isinstance(custom_images, list):
@@ -446,4 +451,4 @@ class MetadataUpdater:
             
         except Exception as e:
             logger.error(f"Error parsing image metadata: {e}", exc_info=True)
-            return None
+            return None