chore(core-flows): set packed_at when fulfillment is created (#8665)

packages/core/core-flows/src/order/workflows/create-fulfillment.ts

@@ -136,6 +136,7 @@ function prepareFulfillmentData({
       items: fulfillmentItems,
       labels: input.labels ?? [],
       delivery_address: shippingAddress as any,
+      packed_at: new Date(),
     },
   }
 }