feat: add endpoint to serve embedded cover art from audio files

public/js/main.js

@@ -57,9 +57,7 @@ function handlePlayTrack(msg) {
   if ($guessTitle) $guessTitle.value = '';
   if ($guessArtist) $guessArtist.value = '';
   if ($answerResult) { $answerResult.textContent=''; $answerResult.className='mt-1 text-sm'; }
-  try {
-    $audio.preload = 'auto';
-  } catch {}
+  try { $audio.preload = 'auto'; } catch {}
   $audio.src = t.url;
   const pf = document.getElementById('progressFill');
   if (pf) {
@@ -68,6 +66,8 @@ function handlePlayTrack(msg) {
   const rd = document.getElementById('recordDisc');
   if (rd) {
     rd.classList.remove('spin-record');
+    // Reset cover to default logo at the start of a new track
+    rd.src = '/hitstar.png';
   }
   const { startAt, serverNow } = msg;
   const now = Date.now();
@@ -134,6 +134,15 @@ function handleReveal(msg) {
   if ($placeArea) {
     $placeArea.classList.add('hidden');
   }
+  // Try to load embedded cover art and replace the center image
+  const rd = document.getElementById('recordDisc');
+  if (rd && track?.id) {
+    const coverUrl = `/cover/${encodeURIComponent(track.id)}`;
+    const img = new Image();
+    img.onload = () => { rd.src = coverUrl; };
+    img.onerror = () => { /* keep default logo */ };
+    img.src = coverUrl + `?t=${Date.now()}`; // bypass cache just in case
+  }
 }
 
 function handleGameEnded(msg) {