fix: Update test fixtures to use correct service method names

- Fixed test_download_progress_websocket: stop() -> stop_downloads()
- Fixed test_download_service: start() -> initialize(), stop() -> stop_downloads()
- Resolved 8 test errors and 3 test failures
- Test status: 970 passing, 31 failing (down from 967 passing, 34 failing, 8 errors)
- All 104 NFO-related tests still passing (100%)

tests/unit/test_image_downloader.py

@@ -1,17 +1,14 @@
 """Unit tests for image downloader."""
 
-import aiohttp
 import io
 from pathlib import Path
 from unittest.mock import AsyncMock, MagicMock, patch
 
+import aiohttp
 import pytest
 from PIL import Image
 
-from src.core.utils.image_downloader import (
-    ImageDownloader,
-    ImageDownloadError,
-)
+from src.core.utils.image_downloader import ImageDownloader, ImageDownloadError
 
 
 @pytest.fixture