Replaces the imperative play/pause/seek/positionSync message soup with a
single host-authored PlaybackState (seq-ordered, anchor-extrapolated,
phase machine: loading/waitingForPeers/paused/playing) that doubles as
the heartbeat, plus guest status reports and host-applied control
requests. Fixes the guest seek-back loop while the host loads (readiness
was keyed on a pre-load !buffering snapshot and heartbeats broadcast
frozen positions), adds real group buffering coordination (stall grace,
scheduled simultaneous resumes, 15s safety timeout), rate-nudge drift
correction with passthrough-aware seek fallback, session-scoped message
handling (no lost messages during episode-switch detach gaps), and an
expected-state ledger replacing the racy remote-action flag.
- Fix guest controls locked on join (use reactive context.select)
- Fix Google TV back button when controls hidden (focus recovery + global fallback)
- Fix profile switch screen focus lost on TV (explicit focus request)
- Add 15s host reconnect grace period with reconnecting overlay
- Add participant join/leave notification toasts
- Default to system language on first launch via findDeviceLocale()
edde746