feat(library): store each album's MusicBrainz release-group id (M483 #5242)

albums.mbid is the release id (Picard's musicbrainz_albumid, one edition).
Lidarr names albums by release group, so re-acquisition and request
completion need that id too (#5241).

Migration 0070 adds albums.release_group_mbid (nullable, non-unique index:
several releases share a group). The scanner reads musicbrainz_releasegroupid
through extractReleaseGroupMBID, writes it on insert and heals it onto
existing rows when NULL. tagReadVersion goes to 3 so the next scan fills
it for the library already indexed, bound by tag reads (no ffprobe, no
decode).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/db/dbq/recommendation.sql.go

@@ -370,7 +370,7 @@ func (q *Queries) ListMostPlayedTracksForUser(ctx context.Context, arg ListMostP
 }
 
 const listRediscoverAlbumsFallbackForUser = `-- name: ListRediscoverAlbumsFallbackForUser :many
-SELECT albums.id, albums.title, albums.sort_title, albums.artist_id, albums.release_date, albums.mbid, albums.cover_art_path, albums.created_at, albums.updated_at, albums.cover_art_source, albums.cover_art_sources_version, artists.name AS artist_name
+SELECT albums.id, albums.title, albums.sort_title, albums.artist_id, albums.release_date, albums.mbid, albums.cover_art_path, albums.created_at, albums.updated_at, albums.cover_art_source, albums.cover_art_sources_version, albums.release_group_mbid, artists.name AS artist_name
 FROM general_likes_albums gla
 JOIN albums  ON albums.id = gla.album_id
 JOIN artists ON artists.id = albums.artist_id
@@ -418,6 +418,7 @@ func (q *Queries) ListRediscoverAlbumsFallbackForUser(ctx context.Context, arg L
 			&i.Album.UpdatedAt,
 			&i.Album.CoverArtSource,
 			&i.Album.CoverArtSourcesVersion,
+			&i.Album.ReleaseGroupMbid,
 			&i.ArtistName,
 		); err != nil {
 			return nil, err
@@ -459,7 +460,7 @@ eligible AS (
     HAVING COALESCE(max(pe.started_at), '1970-01-01'::timestamptz)
            < now() - interval '14 days'
 )
-SELECT albums.id, albums.title, albums.sort_title, albums.artist_id, albums.release_date, albums.mbid, albums.cover_art_path, albums.created_at, albums.updated_at, albums.cover_art_source, albums.cover_art_sources_version, artists.name AS artist_name
+SELECT albums.id, albums.title, albums.sort_title, albums.artist_id, albums.release_date, albums.mbid, albums.cover_art_path, albums.created_at, albums.updated_at, albums.cover_art_source, albums.cover_art_sources_version, albums.release_group_mbid, artists.name AS artist_name
 FROM eligible e
 JOIN albums  ON albums.id = e.album_id
 JOIN artists ON artists.id = albums.artist_id
@@ -510,6 +511,7 @@ func (q *Queries) ListRediscoverAlbumsForUser(ctx context.Context, arg ListRedis
 			&i.Album.UpdatedAt,
 			&i.Album.CoverArtSource,
 			&i.Album.CoverArtSourcesVersion,
+			&i.Album.ReleaseGroupMbid,
 			&i.ArtistName,
 		); err != nil {
 			return nil, err