Add the FavoritesState fields for the Playlists port: two SearchPlaylistItem
sources (playlists-favorites = local Library, playlists-following = Qobuz
followed) + playlists-visible (current sub-tab after search), the transient
sub-tab/search/view-mode strings, and the following-count badge. Add the
FavoritesActions callbacks (playlists-set-sub-tab, search-playlists,
playlists-set-view, playlist-action). Wiring + controller follow.
cc