Add full-featured SpotifyWorker and iTunesWorker background workers to enrich artists, albums, and tracks with external metadata using batch cascading searches, fuzzy name matching, ID validation, and DB backfills. Update RepairWorker to re-read the transfer path from the database each scan, resolve host paths when running in Docker, and trigger immediate rescans when the transfer path changes; remove the static config_manager dependency. Also include supporting changes to the database layer and web UI/server (stats, controls, and styles) to integrate the new workers and reflect updated worker status.
Introduce a RepairWorker to scan the transfer folder and automatically detect/repair broken album track numbers (e.g. the "all tracks = 01" bug). The worker uses mutagen to read/write tags, fuzzy-matches titles against an album tracklist (Spotify/iTunes via a SpotifyClient), updates filenames and the tracks DB file_path when renamed, and caches album tracklists. It also adds DB schema support (repair_status, repair_last_checked, and an index).
Integrates the worker into the web server: initializes and starts the worker, and exposes /api/repair/status, /api/repair/pause and /api/repair/resume endpoints. Adds UI elements (button, tooltip), client-side JS to poll and control the worker, CSS for visuals/animations, and a new image asset (whisoul.png).
