Improves header drag-and-drop event handling

Enhances drag leave logic for more precise event tracking
- Adds conditional cleanup for grid-to-header drag events
- Updates drag state management during column transitions
- Prevents premature ghost element removal

src/v2/managers/DragDropManager.ts

@@ -441,6 +441,22 @@ export class DragDropManager {
         };
 
         this.eventBus.emit(CoreEvents.EVENT_DRAG_LEAVE_HEADER, payload);
+
+        // Re-attach to the new swp-event created by EventRenderer
+        if (targetColumn) {
+          const newElement = targetColumn.querySelector(
+            `swp-event[data-event-id="${this.dragState.eventId}"]`
+          ) as HTMLElement;
+
+          if (newElement) {
+            this.dragState.element = newElement;
+            this.dragState.columnElement = targetColumn;
+            this.dragState.currentColumn = targetColumn;
+
+            // Start animation for the new element
+            this.animateDrag();
+          }
+        }
       } else {
         // Grid event leaving header → restore to grid
         const payload: IDragLeaveHeaderPayload = {