fix: use all album artists for folder naming

internal/app/app.go

@@ -648,10 +648,7 @@ func (m *Main) ripAlbum(ctx context.Context, p provider.Client, source, albumID
 	}
 
 	albumTitle := titleFromMetadata(albumMeta, albumID)
-	albumArtist := jsonutil.NestedString(albumMeta, "artist", "name")
-	if albumArtist == "" {
-		albumArtist = "Unknown"
-	}
+	albumArtist := extractAlbumArtist(albumMeta)
 	releaseDate := jsonutil.StringFromAny(albumMeta["release_date_original"])
 	if releaseDate == "" {
 		releaseDate = jsonutil.StringFromAny(albumMeta["release_date"])
@@ -1224,10 +1221,7 @@ func (m *Main) trackOutputPath(source, id, title, ext string, d *provider.Downlo
 		if albumID == "" {
 			albumID = id
 		}
-		albumArtist := jsonutil.NestedString(trackMeta, "album", "artist", "name")
-		if albumArtist == "" {
-			albumArtist = jsonutil.NestedString(trackMeta, "performer", "name")
-		}
+		albumArtist := extractAlbumArtist(trackMetaAlbum(trackMeta))
 		albumYear := naming.YearFromDate(jsonutil.StringFromAny(trackMeta["release_date_original"]))
 		if albumYear == "Unknown" {
 			albumYear = naming.YearFromDate(jsonutil.StringFromAny(trackMeta["release_date"]))
@@ -1613,3 +1607,42 @@ func isFFmpegMissingError(err error) bool {
 	}
 	return strings.Contains(strings.ToLower(err.Error()), "ffmpeg not found")
 }
+
+func extractAlbumArtist(albumMeta map[string]any) string {
+	if artistsRaw, ok := albumMeta["artists"].([]any); ok {
+		names := make([]string, 0, len(artistsRaw))
+		for _, a := range artistsRaw {
+			artist, ok := a.(map[string]any)
+			if !ok {
+				continue
+			}
+			if name := jsonutil.StringFromAny(artist["name"]); name != "" {
+				names = append(names, name)
+			}
+		}
+		if len(names) > 0 {
+			return displayArtistNames(names)
+		}
+	}
+	if names := stringSliceFromAny(albumMeta["artist_names"]); len(names) > 0 {
+		return displayArtistNames(names)
+	}
+	artist := jsonutil.NestedString(albumMeta, "artist", "name")
+	if artist != "" {
+		return artist
+	}
+	return "Unknown"
+}
+
+func displayArtistNames(names []string) string {
+	switch len(names) {
+	case 0:
+		return ""
+	case 1:
+		return names[0]
+	case 2:
+		return names[0] + " & " + names[1]
+	default:
+		return strings.Join(names[:len(names)-1], ", ") + " & " + names[len(names)-1]
+	}
+}