New favorites_prefs module stores albums view/sort/group + tracks group
in <data-dir>/qbz/favorites_ui.json (search stays transient). Loaded into
FavoritesState on each favorites navigation (before the data applies),
saved on every toolbar change; apply_favorites now re-derives on load so
the restored sort/group take effect (also fixes a latent case where a set
group mode wasn't applied after a tab reload). Album view toggle routes
through an albums-set-view action to persist it.
cc
vicrodh
8355f18e0a