fix:allow item quantity changes only for pending orders

packages/shared/src/order-status.ts

@@ -1,3 +1,9 @@
 export const orderStatuses = ["pending", "processing", "shipped", "cancelled", "refunded"] as const;
 
 export type OrderStatus = (typeof orderStatuses)[number];
+
+// Item quantities can only be adjusted before fulfillment starts. Shared so the UI
+// matches the API rule; the API stays the authoritative check.
+export function canEditOrderItems(status: OrderStatus) {
+  return status === "pending";
+}