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.

tests/services/test_civitai_client.py

@@ -5,6 +5,7 @@ import pytest
 
 from py.services import civitai_client as civitai_client_module
 from py.services.civitai_client import CivitaiClient
+from py.services.errors import RateLimitError
 from py.services.model_metadata_provider import ModelMetadataProviderManager
 
 
@@ -106,6 +107,21 @@ async def test_get_model_by_hash_handles_not_found(monkeypatch, downloader):
     assert error == "Model not found"
 
 
+async def test_get_model_by_hash_propagates_rate_limit(monkeypatch, downloader):
+    async def fake_make_request(method, url, use_auth=True):
+        return False, RateLimitError("limited", retry_after=4)
+
+    downloader.make_request = fake_make_request
+
+    client = await CivitaiClient.get_instance()
+
+    with pytest.raises(RateLimitError) as exc_info:
+        await client.get_model_by_hash("limited")
+
+    assert exc_info.value.retry_after == 4
+    assert exc_info.value.provider == "civitai_api"
+
+
 async def test_download_preview_image_writes_file(tmp_path, downloader):
     client = await CivitaiClient.get_instance()
     target = tmp_path / "preview" / "image.jpg"