Improves all-day event drag and drop

Refactors all-day event drag and drop handling for improved accuracy and performance.

Introduces a shared `ColumnDetectionUtils` for consistent column detection.

Simplifies all-day conversion during drag, placing events in row 1 and calculating the column from the target date.

Implements differential updates during drag end, updating only changed events for smoother transitions.

src/types/EventTypes.ts

@@ -87,6 +87,14 @@ export interface DragMouseLeaveHeaderEventPayload {
   cloneElement: HTMLElement| null;
 }
 
+// Drag column change event payload
+export interface DragColumnChangeEventPayload {
+  draggedElement: HTMLElement;
+  previousColumn: string | null;
+  newColumn: string;
+  mousePosition: MousePosition;
+}
+
 // Header ready event payload
 export interface HeaderReadyEventPayload {
   headerElement: HTMLElement;