fix: prevent notification close on skip and background audio stall

- playCurrent: set _trackChanging flag and update media session metadata
  before changing src, so the pause event fired by src-swap does not
  set playbackState='paused' and dismiss the Samsung cover screen notification
- Remove stalled->load() handler that silently paused audio with no recovery
- Error handler now retries regardless of paused state (load() causes paused)
- Add .catch() to audio.play() in playCurrent

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/main.js

@@ -126,6 +126,7 @@ window.addEventListener('load', () => {
   S.audio.addEventListener('timeupdate', updateProgress);
   S.audio.addEventListener('ended', onEnded);
   S.audio.addEventListener('play', () => {
+    S._trackChanging = false;
     absInterrupt();
     setPlayIcon(true);
     document.getElementById('player-art').classList.add('spinning');
@@ -134,16 +135,16 @@ window.addEventListener('load', () => {
   S.audio.addEventListener('pause', () => {
     setPlayIcon(false);
     document.getElementById('player-art').classList.remove('spinning');
-    if(navigator.mediaSession) navigator.mediaSession.playbackState = 'paused';
+    // Suppress during track change — src swap fires pause before the new track starts
+    if(!S._trackChanging && navigator.mediaSession) navigator.mediaSession.playbackState = 'paused';
   });
   S.previewAudio.addEventListener('timeupdate', updatePreviewProgress);
   S.previewAudio.addEventListener('ended', stopPreview);
 
-  // Recovery: try to resume if audio stalls (network hiccup, background throttle)
-  S.audio.addEventListener('stalled', () => { if(!S.audio.paused) S.audio.load(); });
-  S.audio.addEventListener('waiting', () => { /* let browser handle buffering */ });
+  // stalled = browser buffer ran out briefly; let the browser retry naturally.
+  // The watchdog below catches genuine long freezes.
   S.audio.addEventListener('error', () => {
-    if(!S.audio.paused && S.queue[S.qIdx]) {
+    if(S.queue[S.qIdx]) {
       const t = setTimeout(() => { S.audio.load(); S.audio.play().catch(()=>{}); }, 2000);
       S.audio.addEventListener('play', () => clearTimeout(t), { once: true });
     }