Add a select toggle to the Tracks header that enters multi-select mode
(per-row checkboxes via the shared TrackRow) and shows the shared
MultiSelectBar with Select all / Remove from favorites / Clear. Selection
lives on the rendered tracks-visible rows (mirrors playlist.rs); the
toggle-select router arm and recount gain a Favorites case. Bulk remove
loops remove_favorite, syncs fav_cache, then reloads the tab. Play next /
queue / add-to-playlist / make-offline are deferred (each needs a backend
path: batch enqueue / multi-id picker / offline cache).
cc
vicrodh
e9836184e7