When a user manually matched an artist to a service ID then triggered
enrichment, the worker re-searched by name, failed to find a match,
and overwrote the status back to not_found — despite the ID being
valid. Now both Genius and AudioDB workers check for existing service
IDs before searching by name. If an ID exists (from manual match),
the worker uses it for a direct API lookup to enrich metadata while
preserving the matched status. Added AudioDB lookup-by-ID client
methods for artist, album, and track.
Integrated TheAudioDB as a metadata enrichment source. A background worker scans the library in priority order (artists → albums → tracks), matching entities via fuzzy name comparison and storing style, mood, and AudioDB IDs. Includes rate limiting, 30-day retry for not-found items, and a UI tooltip showing phase-based scan progress.
