Add play_track_next and enqueue_album_next to playback.rs, calling the
core's add_track_next to insert after the current track. Album play-next
inserts tracks in reverse so they land in order, mirroring Tauri's
v2_add_tracks_to_queue_next. Route ("track"/"album", "play-next")
through the on_media_action handler. Add the lucide list-end icon used
for the existing "Add to queue" item.
cc
vicrodh
6203a2db26
