Two related entities mirroring flutter_client/lib/cache/db.dart:
- CachedPlaylists — one row per playlist; `systemVariant` is null for
user playlists and "for_you" / "songs_like_artist" / etc. for
system-generated mixes (used by the add-to-playlist sheet filter)
- CachedPlaylistTracks — composite-PK join table, `position` carries
ordering inside a playlist
DAO surfaces split user vs system playlists at the query layer so
ViewModels don't have to filter — observeUserPlaylists/observeSystemPlaylists.
PlaylistTrackDao gets a deleteByPlaylist for the replace-all pattern
after a sync delta lands.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
bvandeusen
4b38623229