fix: mất âm thanh khi nhấp đôi MIDI item vào Piano Roll - preload instrument bằng dedicated channel (assignTrackMidiChannel) thay vì trkIdx%16

app/static/js/app.jsx

@@ -13500,9 +13500,9 @@ const App = () => {
       var sfId = se.soundfont_id;
       if (sfId) {
         var allTrks = activeTracksRef.current || activeTracks;
-        var trkIdx = 0;
-        for (var ti = 0; ti < allTrks.length; ti++) { if (allTrks[ti].id === trackId) { trkIdx = ti; break; } }
-        var seCh = (se.soundfont_bank === 128 ? 9 : (trkIdx % 16));
+        // Use the track's dedicated channel (same as every playback path) so the
+        // preload matches where piano-roll notes will actually sound.
+        var seCh = assignTrackMidiChannel(track, allTrks);
         window.SonicSF.selectInstrument(seCh, se.soundfont_bank || 0, se.soundfont_program || 0, sfId);
       }
     }

app/templates/index.html

@@ -24,7 +24,7 @@
     <script src="/static/js/services/midiExtractor.js?v=202607281052"></script>
     <script src="/static/js/services/promptTemplateManager.js?v=202607281039"></script>
     <script src="/static/js/services/undoRedoEngine.js?v=202607290941"></script>
-    <script src="/static/js/app.precompiled.js?v=202608031330" defer></script>
+    <script src="/static/js/app.precompiled.js?v=202608031345" defer></script>
     <link rel="stylesheet" href="/static/css/styles.css?v=202607271016">
     <style>
         :root {