A playing active-peer renderer that goes silent left the controller UI
stuck on stale 'playing' (no equivalent of the webplayer's 12s
rendererLost timer). Add a generation-guarded 12s watchdog keyed on the
active peer renderer in the RENDERER_STATE_UPDATED handler: reset on every
update, arm only while playing_state==PLAYING, disarm on
pause/stop/active-change/disconnect. On expiry freeze the projection to
UNKNOWN and emit qconnect:renderer_unreachable; Svelte shows an error
toast (rendererUnreachable, all 5 locales). Reuses the
freeze-projection-to-unknown helper from the ACTIVE_DISCONNECTED path.
cc
vicrodh
a05e8abc25