feat(subsonic): append album version to names in Subsonic API (#5111)

* feat(subsonic): append album version to album names in Subsonic API responses

Add AppendAlbumVersion config option (default: true) that appends the
album version tag to album names in Subsonic API responses, similar to
how AppendSubtitle works for track titles. This affects album names in
childFromAlbum and buildAlbumID3 responses.

Signed-off-by: Deluan <deluan@navidrome.org>

* feat(subsonic): append album version to media file album names in Subsonic API

Add FullAlbumName() to MediaFile that appends the album version tag,
mirroring the Album.FullName() behavior. Use it in childFromMediaFile
and fakePath to ensure media file responses also show the album version.

Signed-off-by: Deluan <deluan@navidrome.org>

* fix(subsonic): use len() check for album version tag to prevent panic on empty slice

Use len(tags) > 0 instead of != nil to safely guard against empty
slices when accessing the first element of the album version tag.

Signed-off-by: Deluan <deluan@navidrome.org>

* fix(subsonic): use FullName in buildAlbumDirectory and deduplicate FullName calls

Apply album.FullName() in buildAlbumDirectory (getMusicDirectory) so
album names are consistent across all Subsonic endpoints. Also compute
al.FullName() once in childFromAlbum to avoid redundant calls.

Signed-off-by: Deluan <deluan@navidrome.org>

* fix: use len() check in MediaFile.FullTitle() to prevent panic on empty slice

Apply the same safety improvement as FullAlbumName() and Album.FullName()
for consistency.

Signed-off-by: Deluan <deluan@navidrome.org>

* test: add tests for Album.FullName, MediaFile.FullTitle, and MediaFile.FullAlbumName

Cover all cases: config enabled/disabled, tag present, tag absent, and
empty tag slice.

Signed-off-by: Deluan <deluan@navidrome.org>

---------

Signed-off-by: Deluan <deluan@navidrome.org>

server/subsonic/browsing.go

@@ -443,7 +443,7 @@ func (api *Router) buildArtist(r *http.Request, artist *model.Artist) (*response
 func (api *Router) buildAlbumDirectory(ctx context.Context, album *model.Album) (*responses.Directory, error) {
 	dir := &responses.Directory{}
 	dir.Id = album.ID
-	dir.Name = album.Name
+	dir.Name = album.FullName()
 	dir.Parent = album.AlbumArtistID
 	dir.PlayCount = album.PlayCount
 	if album.PlayCount > 0 {

server/subsonic/helpers.go

@@ -197,7 +197,7 @@ func childFromMediaFile(ctx context.Context, mf model.MediaFile) responses.Child
 	}
 
 	child.Parent = mf.AlbumID
-	child.Album = mf.Album
+	child.Album = mf.FullAlbumName()
 	child.Year = int32(mf.Year)
 	child.Artist = mf.Artist
 	child.Genre = mf.Genre
@@ -302,7 +302,7 @@ func artistRefs(participants model.ParticipantList) []responses.ArtistID3Ref {
 func fakePath(mf model.MediaFile) string {
 	builder := strings.Builder{}
 
-	builder.WriteString(fmt.Sprintf("%s/%s/", sanitizeSlashes(mf.AlbumArtist), sanitizeSlashes(mf.Album)))
+	builder.WriteString(fmt.Sprintf("%s/%s/", sanitizeSlashes(mf.AlbumArtist), sanitizeSlashes(mf.FullAlbumName())))
 	if mf.DiscNumber != 0 {
 		builder.WriteString(fmt.Sprintf("%02d-", mf.DiscNumber))
 	}
@@ -321,9 +321,10 @@ func childFromAlbum(ctx context.Context, al model.Album) responses.Child {
 	child := responses.Child{}
 	child.Id = al.ID
 	child.IsDir = true
-	child.Title = al.Name
-	child.Name = al.Name
-	child.Album = al.Name
+	fullName := al.FullName()
+	child.Title = fullName
+	child.Name = fullName
+	child.Album = fullName
 	child.Artist = al.AlbumArtist
 	child.Year = int32(cmp.Or(al.MaxOriginalYear, al.MaxYear))
 	child.Genre = al.Genre
@@ -405,7 +406,7 @@ func buildDiscSubtitles(a model.Album) []responses.DiscTitle {
 func buildAlbumID3(ctx context.Context, album model.Album) responses.AlbumID3 {
 	dir := responses.AlbumID3{}
 	dir.Id = album.ID
-	dir.Name = album.Name
+	dir.Name = album.FullName()
 	dir.Artist = album.AlbumArtist
 	dir.ArtistId = album.AlbumArtistID
 	dir.CoverArt = album.CoverArtID().String()