The artwork pipeline wrote a decoded cover into the SOURCE model
(FavoritesState.albums / .tracks) by index, but the views render the
derived albums-visible / albums-grouped / tracks-visible models, which
are independent clones whenever a sort/group/search is active. So a
late-arriving cover never reached the rendered card (grey until a
re-derive). Add favorites::set_album_artwork / set_track_artwork to also
propagate the cover by id into the rendered model(s); apply_artwork calls
them for FavoriteAlbum / FavoriteTrack. The disk cache was already in use;
this was purely the render target.
cc
vicrodh
39c8e86d7b