fix: click empty space always draws note regardless of tool

Removed tool check for drawing. Default tool back to 'select'.
Click + drag on empty piano roll = draw notes, no tool switch needed.

app/static/js/app.jsx

@@ -4544,7 +4544,7 @@ const AIPresetModal = ({ isOpen, onClose }) => {
 };
 
 const PianoRollTabEditor = ({ st, zoom, bpm, viewportWidth, onClose, onUpdateNotes, onSaveNotes, setSubTabs, onPlayPause, onStop, isPlaying, playPreviewNote, showToast }) => {
-  const [activeRollTool, setActiveRollTool] = React.useState('pen');
+  const [activeRollTool, setActiveRollTool] = React.useState('select');
   const [snapVal, setSnapVal] = React.useState('1/16');
   const [ccMode, setCcMode] = React.useState('velocity');
   const [rollZoom, setRollZoom] = React.useState(60); // local horizontal zoom factor
@@ -5045,7 +5045,7 @@ const PianoRollTabEditor = ({ st, zoom, bpm, viewportWidth, onClose, onUpdateNot
         startOffsetPitch: pitch - clickedNote.pitch,
         selectedNotesOffset: selectedNotesOffset
       });
-    } else if (activeRollTool === 'pen') {
+    } else {
       // Click on empty space with pen tool: DRAW a new note (brush mode with visitedPitches)
       pushToUndo(notes);
       const start = getSnapBeat(beat, snapVal);