fix: FLAC, Ogg and Opus tracks carry their MusicBrainz recording id from the tag: one reader in library gives the scanner, the backfills and the importer the same ids, and the next scan re-reads the library (#5637)

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

internal/library/scanner.go

@@ -64,7 +64,12 @@ var audioExtensions = map[string]bool{
 //	   and MP4 (#2500). dhowden/tag kept only the last, and 3,658 of the
 //	   operator's 4,092 FLACs declare more than one, so most of their genres
 //	   were never stored.
-const tagReadVersion int16 = 4
+//	5: the recording id is read from FLAC, Ogg Vorbis and Opus (#5637). Picard
+//	   calls it MUSICBRAINZ_TRACKID there and dhowden/tag files that under the
+//	   release-track name, so every Vorbis-tagged track came in without its
+//	   tag id and waited on an AcoustID lookup. A re-read stores the tag id,
+//	   over a looked-up one (D4).
+const tagReadVersion int16 = 5
 
 type Stats struct {
 	Scanned int `json:"scanned"`
@@ -272,9 +277,9 @@ func (s *Scanner) scanFile(
 	if err != nil {
 		return pgtype.UUID{}, false, fmt.Errorf("tag read: %w", err)
 	}
-	albumMBID, artistMBID := extractMBIDs(meta)
-	recordingMBID := extractRecordingMBID(meta)
-	releaseGroupMBID := extractReleaseGroupMBID(meta)
+	ids := ReadTagMBIDs(meta)
+	albumMBID, artistMBID := ids.Release, ids.Artist
+	recordingMBID, releaseGroupMBID := ids.Recording, ids.ReleaseGroup
 
 	artistName := meta.Artist()
 	if artistName == "" {