Operator's model: offline, surface the cache-backed pools right
where the (now play-disabled, S4a) system playlists sit, so Home
still has something to play.
- ShuffleSource gains recentlyPlayed() (cache by lastPlayedAt desc,
liked included) and liked() (cache ∩ liked set); shared _refs()
materializes ordered ids from cached_tracks/artists/albums.
Shuffle-all reuses the same recency walk.
- Home Playlists row: when offlineProvider is true, prepend two
tiles — "Recently played" / "Liked" — sized to PlaylistCard.
Tap → shuffle+play that pool from cache; empty → snackbar.
System tiles still render (play disabled per S4a) beside them.
- offline=false (online + all widget tests) → no extra tiles;
placeholder-count tests unaffected.
Closes the S4 thread of the #427 umbrella (S4a + S4b).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>