Replaced track-count-only release selection with deterministic scoring
across 6 factors: track count match (40pts), release status (10pts),
country preference with US/worldwide bias (10pts), format preference
favoring Digital/CD over Vinyl/Cassette (10pts), barcode presence (3pts),
and date completeness (2pts). Same inputs always produce the same release.
Also fixed critical bug: _embed_source_ids was missing the context
parameter, silently skipping ALL source ID tag embedding since the
MusicBrainz consistency commit. Now passes context from the caller.
Before album tracks start post-processing, pre-populate the MusicBrainz
release cache with ONE verified release. All tracks then hit the cache
during per-track processing and get the same release MBID — no second pass,
no file lock contention, tags correct on first write.
Handles edition name mismatches (Spotify says 'Super Deluxe', MB says
just the base name) by stripping qualifiers and searching again.
Validates track count to pick the right edition. Three download paths
covered: download missing modal, enhanced album, and matched album.