New qbz_app::offline_mode (frontend-agnostic, ADR-006): three-state mode
machine (Online / RealOffline session-scoped / InducedOffline persisted),
Tauri-compatible offline_settings.db store with the issue #279
stream_first_track snapshot, and a layered connectivity actor (default-route
signal on Linux, audio liveness window, IP-literal + vendor-diverse strict
probes, asymmetric hysteresis with confirmation burst, captive-portal and
suspend/resume handling).
qbz-qobuz gains the process-wide offline_gate and ApiError::OfflineMode (the
single Qobuz choke point; HTTP funnel wiring lands next).
SubscriptionStateStore gains offline_playback_allowed: binary 30-day-grace
playback gate for the offline cache, never a preview-degradation path.
cc
vicrodh
edae9d2463