Prowlarr non-category search fallback, bypass optimizations, and code cleanup (#379)

- Prowlarr: Added automatic fallback to search without category filter
when indexers return no results with book category (7000), improving
compatibility with indexers that don't support category filtering
- Prowlarr: Hide language filter in UI since Prowlarr has unreliable
language metadata
- Bypass: Refactored internal bypasser with code cleanup, extracted
helper functions, and added health check capability
  - Bypass: Added fingerprint module for screen size handling
- qBittorrent: Fixed connection test to use web API version instead of
app version
- Frontend: Added supported_filters config to control which filters
display per source
- Auth: Improved CWA database path validation (now uses Path object
properly)

docker-compose.dev.yml

@@ -15,9 +15,6 @@ services:
       - ./.local/ingest:/cwa-book-ingest
       - ./.local/log:/var/log/cwa-book-downloader
       - ./.local/tmp:/tmp/cwa-book-downloader
-      # Mount source code for development (no rebuild needed for Python code changes)
       - ./cwa_book_downloader:/app/cwa_book_downloader:ro
-      # Download client volume - required for Prowlarr/torrent/usenet integration
-      # IMPORTANT: Both sides of this mount must match your download client's volume mount exactly.
-      # Example: if qBittorrent has "/mnt/storage/downloads:/data/torrents", use the same here:
-      # - /mnt/storage/downloads:/data/torrents
+      # Download client mount (must match your torrent/usenet client's volume)
+      # - /path/to/downloads:/downloads