Swap the passive single-cover FavPlaylistCard tile for the shared
discover/PlaylistCard (collage + hover overlay play/fav/more + context
menu) over playlists-visible, and add the Library/Following underline
sub-tab selector (no pills, ADR-008) above the grid with per-sub-tab and
search-empty states. Extend the shared PlaylistCard with a body-opens
prop so a favorites card-body click opens the playlist while the play
button plays (discover/search keep body=play, unchanged). Add the
Playlists search box to the row-2 toolbar. Remove the dead
FavoritePlaylistItem struct + playlists field + FavPlaylistCard.
cc