fix: Ctrl+click empty space starts sweep select with yellow cursor

Line 1163 called onSweepSelectStart which set up sweep
state (yellow selection rectangle). Mousemove then
selected all items in the sweep range. Changed to
onClearSelection = () => setSelectedItemIds(new Set())
which only clears selection without starting sweep.

app/static/js/app.jsx

@@ -414,6 +414,7 @@ const WaveformLane = ({
   onSplitTrackAtTime,
   onEditClipInSubTab,
   selectedItemIds,
+  onClearSelection,
   onSweepSelectStart,
   snapValue,
   bpm,
@@ -1160,11 +1161,11 @@ const WaveformLane = ({
         return;
       }
 
-      // Ctrl+Click on empty space: sweep select (deselect all via onSweepSelectStart)
+      // Ctrl+Click on empty space: deselect all, no sweep select
       if (e.ctrlKey && !clickedClip && !hitItem) {
         e.preventDefault();
         e.stopPropagation();
-        if (onSweepSelectStart) onSweepSelectStart(track.id, time);
+        if (onClearSelection) onClearSelection();
         return;
       }
       onPlayheadSet(time);
@@ -16622,6 +16623,7 @@ const App = () => {
          onSelectTrack: setSelectedTrackId,
          markers: track.markers,
          onTrackLaneMouseDown: handleTrackLaneMouseDown,
+         onClearSelection: () => setSelectedItemIds(new Set()),
          onSweepSelectStart: handleSweepSelectStart,
          onDeselectItem: handleDeselectItem,
          onAddToSelection: handleAddToSelection,