History/Hidden/Requests/PlaylistsList/AddToPlaylist/Home/Liked/Library
each had its own sealed interface with Loading/Empty/Success(payload)/
Error variants. Collapsed to the generic shared/UiState<T> introduced
in the prior commit. Library carries two lists (artists + albums) so
its payload is wrapped in a new LibraryData record; the test was
updated to assert against UiState.Success<LibraryData>.
The 3 detail screens (Artist/Album/Playlist Detail) keep their own
sealed interfaces for now since they include a Loading(seed: ...)
variant that does not fit UiState<T>.
bvandeusen
810e3126c2