fix: right-click delete no menu + scale only for brush drag

- Separate swallowContextMenuRef (not tied to rightClickDragRef) so
  menu is skipped on right-click delete
- Initial click draw uses raw pitch, not snapPitchToScale (scale only
  applies during brush-drag in mousemove)

app/static/js/app.jsx

@@ -4922,7 +4922,7 @@ const PianoRollTabEditor = ({ st, zoom, bpm, viewportWidth, onClose, onUpdateNot
         pushToUndo(notes);
         setNotes(prev => prev.filter(n => n.id !== clickedNote.id));
         setSelectedNoteIds(prev => prev.filter(id => id !== clickedNote.id));
-        rightClickDragRef.current.erasedNote = true;
+        swallowContextMenuRef.current = true;
         showToast('Đã xóa nốt!', 'info');
       } else {
         rightClickDragRef.current = { active: true, startX: e.clientX, startY: e.clientY };
@@ -5056,7 +5056,7 @@ const PianoRollTabEditor = ({ st, zoom, bpm, viewportWidth, onClose, onUpdateNot
       const noteId = 'note_' + Date.now() + Math.random().toString(36).substr(2, 5);
       const newNote = {
         id: noteId,
-        pitch: snapPitchToScale(pitch, selectedScale),
+        pitch: pitch,
         start_beat: start,
         duration_beats: initialDur,
         velocity: brushVelocityRef.current,
@@ -5252,8 +5252,8 @@ const PianoRollTabEditor = ({ st, zoom, bpm, viewportWidth, onClose, onUpdateNot
 
   const handleContextMenu = (e) => {
     e.preventDefault();
-    if (rightClickDragRef.current.erasedNote) {
-      rightClickDragRef.current.erasedNote = false;
+    if (swallowContextMenuRef.current) {
+      swallowContextMenuRef.current = false;
       return;
     }
     const pos = { x: e.clientX, y: e.clientY, parentKey: null };
@@ -5263,6 +5263,7 @@ const PianoRollTabEditor = ({ st, zoom, bpm, viewportWidth, onClose, onUpdateNot
 
   const ccDragRef = React.useRef(null);
   const rightClickDragRef = React.useRef({ active: false, startX: 0, startY: 0 });
+  const swallowContextMenuRef = React.useRef(false);
 
   const handleCCMouseDown = (e) => {
     const canvas = ccCanvasRef.current;