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).