feat(civitai): add rate limiting support and error handling

- Add RateLimitError import and _make_request wrapper method to handle rate limiting
- Update API methods to use _make_request wrapper instead of direct downloader calls
- Add explicit RateLimitError handling in API methods to properly propagate rate limit errors
- Add _extract_retry_after method to parse Retry-After headers
- Improve error handling by surfacing rate limit information to callers

These changes ensure that rate limiting from the Civitai API is properly detected and handled, allowing callers to implement appropriate backoff strategies when rate limits are encountered.

py/services/metadata_service.py

@@ -1,6 +1,7 @@
 import os
 import logging
 from .model_metadata_provider import (
+    ModelMetadataProvider,
     ModelMetadataProviderManager, 
     SQLiteModelMetadataProvider,
     CivitaiModelMetadataProvider,
@@ -68,10 +69,10 @@ async def initialize_metadata_providers():
     # Set up fallback provider based on available providers
     if len(providers) > 1:
         # Always use Civitai API (it has better metadata), then CivArchive API, then Archive DB
-        ordered_providers = []
-        ordered_providers.extend([p[1] for p in providers if p[0] == 'civitai_api'])
-        ordered_providers.extend([p[1] for p in providers if p[0] == 'civarchive_api'])
-        ordered_providers.extend([p[1] for p in providers if p[0] == 'sqlite'])
+        ordered_providers: list[tuple[str, ModelMetadataProvider]] = []
+        ordered_providers.extend([p for p in providers if p[0] == 'civitai_api'])
+        ordered_providers.extend([p for p in providers if p[0] == 'civarchive_api'])
+        ordered_providers.extend([p for p in providers if p[0] == 'sqlite'])
         
         if ordered_providers:
             fallback_provider = FallbackMetadataProvider(ordered_providers)