fix: a file tagged with no release group joins the same-named album its folder holds

Under e45561e2 a file with no group tag took the oldest same-named album row,
which left three of Weezer's 1994 bonus tracks on the 2016 album. The lookup
now ranks same-named rows by how many tracks they hold from the file's
folder; tagReadVersion 8 re-places the existing ones.

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

internal/library/scanner.go

@@ -78,7 +78,10 @@ var audioExtensions = map[string]bool{
 //	   (resolveAlbum). Weezer's six self-titled albums were one 118-track row,
 //	   so their merges, wants and upgrades all counted as one album; a re-read
 //	   files each existing track under its own album.
-const tagReadVersion int16 = 7
+//	8: a file tagged with no release group joins the same-named album that
+//	   already holds a track from its folder. Under 7 it took the oldest row,
+//	   which left three of Weezer's 1994 bonus tracks on the 2016 album.
+const tagReadVersion int16 = 8
 
 type Stats struct {
 	Scanned int `json:"scanned"`
@@ -319,7 +322,7 @@ func (s *Scanner) scanFile(
 	if err != nil {
 		return pgtype.UUID{}, false, fmt.Errorf("artist: %w", err)
 	}
-	album, err := s.resolveAlbum(ctx, q, artist.ID, albumTitle, meta.Year(), albumMBID, releaseGroupMBID)
+	album, err := s.resolveAlbum(ctx, q, artist.ID, albumTitle, meta.Year(), albumMBID, releaseGroupMBID, filepath.Dir(path))
 	if err != nil {
 		return pgtype.UUID{}, false, fmt.Errorf("album: %w", err)
 	}
@@ -565,8 +568,8 @@ func (s *Scanner) resolveArtist(ctx context.Context, q *dbq.Queries, name, mbid
 	return artist, nil
 }
 
-func (s *Scanner) resolveAlbum(ctx context.Context, q *dbq.Queries, artistID pgtype.UUID, title string, year int, mbid, releaseGroupMBID string) (dbq.Album, error) {
-	lookup := dbq.GetAlbumByArtistAndTitleParams{ArtistID: artistID, Title: title}
+func (s *Scanner) resolveAlbum(ctx context.Context, q *dbq.Queries, artistID pgtype.UUID, title string, year int, mbid, releaseGroupMBID, dir string) (dbq.Album, error) {
+	lookup := dbq.GetAlbumByArtistAndTitleParams{ArtistID: artistID, Title: title, Dir: dir}
 	if releaseGroupMBID != "" {
 		rg := releaseGroupMBID
 		lookup.ReleaseGroupMbid = &rg