Wraps each cold-load branch in a Crossfade and replaces the
centered spinner with skeleton tile grids/lists that match the
real layout's geometry so the reveal doesn't reflow:
* LibraryScreen Artists tab → SkeletonArtistsGrid (12 SkeletonArtistTile
in adaptive 144dp grid).
* LibraryScreen Albums tab → SkeletonAlbumsGrid (12 SkeletonAlbumTile
in adaptive 176dp grid).
* AlbumDetail → SkeletonTrackList (8 SkeletonTrackRow).
* ArtistDetail → SkeletonArtistAlbumsGrid (9 SkeletonAlbumTile,
176dp adaptive grid mirroring ArtistBody's albums grid).
* PlaylistDetail → SkeletonPlaylistTrackList (8 SkeletonTrackRow).
Drops now-unused LoadingCentered helpers from Library / AlbumDetail /
ArtistDetail / PlaylistDetail per the no-dead-code rule.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
bvandeusen
89203fc4a1