New MusicBrainz tab in Enhanced and Global search — finds tracks and
albums on MusicBrainz's community database with Cover Art Archive
images. Covers obscure tracks that Spotify/Deezer/iTunes miss.
- core/musicbrainz_search.py: search adapter with Track/Artist/Album
dataclasses, Cover Art Archive integration, smart query parsing
- Albums deduplicated (keeps best version with date and art)
- No artist results shown (MusicBrainz has no artist images)
- Album detail with full tracklist for download modal
- Smart word-boundary splitting for queries without separators
- Global search results container widened from 620px to 920px
- UI version bumped to 2.32
