Enhance Outbound and Excel Service Functionality

- Added `inventory_unit` to the item selection query in the outbound controller to improve data retrieval.
- Updated the multi-table Excel service to exclude overlapping headers between parent and child levels, ensuring accurate data insertion.
- Introduced new category combobox components for better user interaction in the supplied item page.
- Enhanced the inbound-outbound page to correctly map user IDs, including super admin handling for user information retrieval.

(TASK: ERP-XXX)

backend-node/src/controllers/outboundController.ts

@@ -740,7 +740,7 @@ export async function getItems(req: AuthenticatedRequest, res: Response) {
 		const pool = getPool();
 		const result = await pool.query(
 			`SELECT
-        id, item_number, item_name, size AS spec, material, unit,
+        id, item_number, item_name, size AS spec, material, unit, inventory_unit,
         COALESCE(width::text, '') AS width,
         COALESCE(height::text, '') AS height,
         COALESCE(thickness::text, '') AS thickness,