fix: use crosshair cursor for arrange-drop cue instead of I-beam

The I-beam read as a text-editing cursor rather than a timeline placement point.

src/shell/panel/panel_drag.cpp

@@ -157,7 +157,7 @@ void applyDropCue(DropCue cue) {
     const char* idc = nullptr;
     switch (cue) {
         case DropCue::Instrument:    idc = IDC_HAND;   break;
-        case DropCue::ArrangeInsert: idc = IDC_IBEAM;  break;  // an insertion point on a timeline
+        case DropCue::ArrangeInsert: idc = IDC_CROSS;  break;  // I-beam read as text-edit, not a timeline placement point
         case DropCue::Refuse:        idc = IDC_NO;     break;
         case DropCue::OsOwned:       return;  // reached once per move resolving to OsHandoff,
                                               // right before handOffToOs is attempted; the OS