fix(player): cross-device resume — push queue position on pause + all exit paths

Server queue position was effectively pinned at 0 because syncQueueToServer
only fired on track-change, seek, and queue edits (with a 5s debounce). A
user listening for minutes without seeking would close the app and the
server still held position=0, so a second device restarted the track.

Three pieces:
- 15s heartbeat from audio:progress flushes the live position while playing.
- pause() flushes immediately so a quick close after pause is captured.
- Tray "Exit" and macOS Cmd+Q used to call app.exit(0) directly, bypassing
  the JS close handler. Both now emit a new app:force-quit event that
  shares the same flush + Orbit-teardown path as window:close-requested,
  and exit_app stops the audio engine on its way out.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/store/playerStore.ts

@@ -813,9 +813,12 @@ let bytePreloadingId: string | null = null;
 
 // ─── Server queue sync ─────────────────────────────────────────────────────────
 let syncTimeout: ReturnType<typeof setTimeout> | null = null;
+let lastQueueHeartbeatAt = 0;
+
 function syncQueueToServer(queue: Track[], currentTrack: Track | null, currentTime: number) {
   if (syncTimeout) clearTimeout(syncTimeout);
   syncTimeout = setTimeout(() => {
+    syncTimeout = null;
     const ids = queue.slice(0, 1000).map(t => t.id);
     const pos = Math.floor(currentTime * 1000);
     savePlayQueue(ids, currentTrack?.id, pos).catch(err => {
@@ -824,6 +827,30 @@ function syncQueueToServer(queue: Track[], currentTrack: Track | null, currentTi
   }, 5000);
 }
 
+// Cancel any pending debounced sync and push the current position
+// immediately. Used by the playback heartbeat, pause(), and the
+// app-close handler — all paths where a user might switch to another
+// device and expect to resume from the right spot.
+function flushQueueSyncToServer(queue: Track[], currentTrack: Track | null, currentTime: number): Promise<void> {
+  if (syncTimeout) {
+    clearTimeout(syncTimeout);
+    syncTimeout = null;
+  }
+  if (!currentTrack || queue.length === 0) return Promise.resolve();
+  lastQueueHeartbeatAt = Date.now();
+  const ids = queue.slice(0, 1000).map(t => t.id);
+  const pos = Math.floor(currentTime * 1000);
+  return savePlayQueue(ids, currentTrack.id, pos).catch(err => {
+    console.error('Failed to flush play queue to server', err);
+  });
+}
+
+export function flushPlayQueuePosition(): Promise<void> {
+  const s = usePlayerStore.getState();
+  if (s.currentRadio) return Promise.resolve();
+  return flushQueueSyncToServer(s.queue, s.currentTrack, s.currentTime);
+}
+
 // ─── Audio event handlers (called from initAudioListeners) ───────────────────
 
 function handleAudioPlaying(_duration: number) {
@@ -875,6 +902,16 @@ function handleAudioProgress(current_time: number, duration: number) {
   const progress = displayTime / dur;
   usePlayerStore.setState({ currentTime: displayTime, progress, buffered: 0 });
 
+  // Heartbeat: push current position to the server every 15 s while
+  // playing so cross-device resume works even on a hard close — pause()
+  // and the close handler flush on top of this for clean shutdowns.
+  if (store.isPlaying && !store.currentRadio) {
+    const now = Date.now();
+    if (now - lastQueueHeartbeatAt >= 15_000) {
+      void flushQueueSyncToServer(store.queue, track, displayTime);
+    }
+  }
+
   // Scrobble at 50%: Last.fm + Navidrome (updates play_date / recently played)
   if (progress >= 0.5 && !store.scrobbled) {
     usePlayerStore.setState({ scrobbled: true });
@@ -1936,6 +1973,12 @@ export const usePlayerStore = create<PlayerState>()(
         } else {
           invoke('audio_pause').catch(console.error);
           isAudioPaused = true;
+          // Flush position so a quick close after pause still leaves the
+          // server with the right resume point for other devices.
+          const s = get();
+          if (s.currentTrack) {
+            void flushQueueSyncToServer(s.queue, s.currentTrack, s.currentTime);
+          }
         }
         set({ isPlaying: false, scheduledPauseAtMs: null, scheduledPauseStartMs: null, scheduledResumeAtMs: null, scheduledResumeStartMs: null });
       },