fix: piano roll dropdown lists tracks only, not every MIDI item

app/static/js/app.jsx

@@ -7396,14 +7396,24 @@ const beatSec = 60.0 / (parseInt(bpm) || 120);
     }, React.createElement("div", {
       className: "flex items-center gap-4"
     }, React.createElement("select", {
-      value: st.target_id || '',
+      value: st.trackId || '',
-      onChange: function(e) { handleSwitchMidiItem(e.target.value); },
+      onChange: function(e) {
+        var trkId = e.target.value;
+        var trkSel = (activeTracks || []).find(function(t) { return t.id === trkId; });
+        if (trkSel && trkSel.midiItems && trkSel.midiItems.length) handleSwitchMidiItem(trkSel.midiItems[0].id);
+      },
       className: "bg-zinc-800 border border-zinc-700 text-yellow-500 font-bold text-xs rounded px-1.5 py-0.5 outline-none focus:border-yellow-500 max-w-[180px] uppercase"
-    }, allMidiItems.map(function(m) {
+    }, (function() {
-      return React.createElement("option", { key: m.id, value: m.id },
+      var seenTrackOpts = {};
-        (m._trackName || '') + ' - ' + (m.name || 'MIDI')
+      var trackOpts = [];
-      );
+      (activeTracks || []).forEach(function(t) {
-    })), activeParentTrackName ? React.createElement("span", {
+        if (!t.midiItems || !t.midiItems.length) return;
+        if (seenTrackOpts[t.id]) return;
+        seenTrackOpts[t.id] = true;
+        trackOpts.push(React.createElement("option", { key: t.id, value: t.id }, t.name || t.id));
+      });
+      return trackOpts;
+    }())), activeParentTrackName ? React.createElement("span", {
       className: "text-[9px] text-zinc-500 ml-1"
     }, "(Belongs to: ", React.createElement("span", { className: "text-zinc-400 font-semibold" }, activeParentTrackName), ")") : null, React.createElement("div", {
       className: "flex items-center gap-1 text-xs"