fix: migrations, auth, providers health check, E2E tests, remove neko-sama

- Add proper Alembic initial migration (0001_initial_schema.py)
- Migrate refresh tokens from JSON file to SQLite (RefreshTokenTable)
- Remove Neko-Sama provider entirely (redirects to Gupy, not a host)
- Fix provider health check always showing UNKNOWN
  - Run check_all_health() on startup
  - Fix POST /providers/health/check background task bug
  - Add HTMX refresh after manual health check trigger
- Fix anime search relevance scoring with MIN_RELEVANCE_THRESHOLD=0.5
- Replace bare 'except:' with 'except Exception:' across codebase
- Add Playwright E2E test suite (12 tests, auth setup, helpers)
- Fix toast container blocking clicks via pointer-events: none
- Remove obsolete Jest/Vite test files and config
- Clean up obsolete test_watchlist scripts
- Update sonarr model comment for active providers

app/sonarr_handler.py

@@ -17,7 +17,7 @@ from app.models.sonarr import (
     SonarrDownloadRequest
 )
 from app.models import DownloadRequest
-from app.downloaders import get_downloader, AnimeSamaDownloader, NekoSamaDownloader, AnimeUltimeDownloader, VostfreeDownloader
+from app.downloaders import get_downloader, AnimeSamaDownloader, AnimeUltimeDownloader, VostfreeDownloader
 
 # Configure logging
 logger = logging.getLogger(__name__)
@@ -205,7 +205,6 @@ class SonarrHandler:
         """Get downloader instance for provider"""
         providers = {
             "anime-sama": AnimeSamaDownloader(),
-            "neko-sama": NekoSamaDownloader(),
             "anime-ultime": AnimeUltimeDownloader(),
             "vostfree": VostfreeDownloader()
         }