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_metadata_sync_service.py

@@ -4,6 +4,7 @@ from unittest.mock import AsyncMock
 
 import pytest
 
+from py.services.errors import RateLimitError
 from py.services.metadata_sync_service import MetadataSyncService
 
 
@@ -340,6 +341,37 @@ async def test_fetch_and_update_model_falls_back_to_sqlite_after_civarchive_fail
     helpers.metadata_manager.save_metadata.assert_awaited()
 
 
+@pytest.mark.asyncio
+async def test_fetch_and_update_model_returns_rate_limit_error(tmp_path):
+    rate_error = RateLimitError("limited", retry_after=7)
+    default_provider = SimpleNamespace(
+        get_model_by_hash=AsyncMock(side_effect=rate_error),
+        get_model_version=AsyncMock(),
+    )
+    helpers = build_service(default_provider=default_provider)
+
+    model_path = tmp_path / "model.safetensors"
+    model_data = {
+        "file_path": str(model_path),
+        "model_name": "Local",
+    }
+    update_cache = AsyncMock()
+
+    ok, error = await helpers.service.fetch_and_update_model(
+        sha256="deadbeef",
+        file_path=str(model_path),
+        model_data=model_data,
+        update_cache_func=update_cache,
+    )
+
+    assert ok is False
+    assert error is not None and "Rate limited" in error
+    assert "7" in error
+    helpers.metadata_manager.save_metadata.assert_not_awaited()
+    update_cache.assert_not_awaited()
+    helpers.provider_selector.assert_not_awaited()
+
+
 @pytest.mark.asyncio
 async def test_relink_metadata_fetches_version_and_updates_sha(tmp_path):
     provider = SimpleNamespace(