feat: add license information handling for Civitai models

Add license resolution utilities and integrate license information into model metadata processing. The changes include:

- Add `resolve_license_payload` function to extract license data from Civitai model responses
- Integrate license information into model metadata in CivitaiClient and MetadataSyncService
- Add license flags support in model scanning and caching
- Implement CommercialUseLevel enum for standardized license classification
- Update model scanner to handle unknown fields when extracting metadata values

This ensures proper license attribution and compliance when working with Civitai models.

py/services/civitai_client.py

@@ -6,6 +6,7 @@ from typing import Any, Optional, Dict, Tuple, List, Sequence
 from .model_metadata_provider import CivitaiModelMetadataProvider, ModelMetadataProviderManager
 from .downloader import get_downloader
 from .errors import RateLimitError, ResourceNotFoundError
+from ..utils.civitai_utils import resolve_license_payload
 
 logger = logging.getLogger(__name__)
 
@@ -420,6 +421,10 @@ class CivitaiClient:
         model_info['tags'] = model_data.get("tags", [])
         version['creator'] = model_data.get("creator")
 
+        license_payload = resolve_license_payload(model_data)
+        for field, value in license_payload.items():
+            model_info[field] = value
+
     async def get_model_version_info(self, version_id: str) -> Tuple[Optional[Dict], Optional[str]]:
         """Fetch model version metadata from Civitai