Fix sleep bug, fix menu return

src/lib/stores/sleepTimer.ts

@@ -58,6 +58,14 @@ function createSleepTimerStore() {
 
 export const sleepTimer = createSleepTimerStore();
 
+/**
+ * Incremented each time the backend reports the time-based sleep timer
+ * expired. The backend stops its own (MPV/ExoPlayer) playback itself, but
+ * HTML5 video on Linux plays in the webview outside the backend's control —
+ * VideoPlayer watches this signal and pauses the <video> element.
+ */
+export const sleepTimerExpiredSignal = writable(0);
+
 // Derived stores for convenient access
 export const sleepTimerMode = derived(sleepTimer, ($s) => $s.mode);