New shared TrackPlayCell for the track-row leading slot, ported 1:1 from
the Tauri track rows: at rest it shows the cover thumbnail or track
number; on row hover a play triangle; for the current track an animated
three-bar equalizer, swapping to a pause glyph on hover. Clicking a
non-current cell plays the track, clicking the current one toggles
play/pause. Wired into the search, album-page and artist-page track
rows.
cc
vicrodh
7efb83c075