- offline.rs: constructs + owns a per-user OfflineCacheState (same index.db +
library.db paths as Tauri, so the offline store is shared across frontends);
activated on login/restore, torn down on logout (hooks in auth.rs).
- playback.rs: play_audible + the gapless trigger now route through QbzCore's
play_track_resolved / fetch_for_gapless_resolved, so an offline-cached track
resolves from disk (decrypt -> play_data) before hitting the network. The
unlock-animation sink is None for now (padlock lands with the Slice 2 UI).
qbz-slint compiles clean. Offline PLAYBACK now works in Slint; the "Make
offline" trigger UI + per-row status + the padlock are next (Slice 2).
cc
vicrodh
1413cec626