- Add SaveAlbumTracks to TrackRepository for batch track caching
- Extend album loadRelations to join album_artists with artist data
- Cache album tracks in GetAlbumTracks after provider fetch
- Ensure artists cached when fetching single album
- gRPC service with MusicBrainz provider
- PostgreSQL schema with migrations
- Service layer with database-first caching
- Repository pattern for data access
- YAML configuration support
- Research documentation for 17 music metadata projects