Update test files with refinements and fixes

- test_anime_endpoints.py: Minor updates
- test_download_retry.py: Refinements
- test_i18n.js: Updates
- test_tmdb_client.py: Improvements
- test_tmdb_rate_limiting.py: Test enhancements
- test_user_preferences.js: Updates

tests/unit/test_download_retry.py

@@ -425,10 +425,12 @@ class TestExponentialBackoff:
     @pytest.mark.asyncio
     async def test_image_downloader_retry_with_backoff(self):
         """Test that ImageDownloader implements exponential backoff."""
-        from src.core.utils.image_downloader import ImageDownloader, ImageDownloadError
         from pathlib import Path
-        import aiohttp
         from unittest.mock import MagicMock
+
+        import aiohttp
+
+        from src.core.utils.image_downloader import ImageDownloader, ImageDownloadError
         
         downloader = ImageDownloader(max_retries=3, retry_delay=0.1)