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.

refs/target_version.json

@@ -11,7 +11,11 @@
     "type": "LORA",
     "nsfw": false,
     "description": "description",
-    "tags": ["style"]
+    "tags": ["style"],
+    "allowNoCredit": true,
+    "allowCommercialUse": ["Sell"],
+    "allowDerivatives": true,
+    "allowDifferentLicense": true
   },
   "files": [
     {