feat: don't show track number when there isn't one

gmus-web/src/components/ui/cmus/views/songs.tsx

@@ -33,7 +33,8 @@ const Row = namedMemo<{ index: number; data: SongData[]; style: CSSProperties }>
     return (
       <Styled.Song active={active} parentActive={parentActive} style={style} highlight={highlight}>
         <NoWrapFill>
-          {song.track} - {song.title || 'Untitled Track'}
+          {song.track ? `${song.track} - ` : ''}
+          {song.title || 'Untitled Track'}
         </NoWrapFill>
       </Styled.Song>
     );