feat(core-flows): Emit cart trasnferred customer (#12425)

**What**
When a cart is transferred emit an event notifying of the action with the cart id and the customer id

.changeset/serious-plums-hope.md

@@ -0,0 +1,6 @@
+---
+"@medusajs/core-flows": patch
+"@medusajs/utils": patch
+---
+
+feat(core-flows): Emit cart trasnferred customer

packages/core/core-flows/src/cart/workflows/transfer-cart-customer.ts

@@ -6,9 +6,10 @@ import {
   WorkflowData,
   WorkflowResponse,
 } from "@medusajs/framework/workflows-sdk"
-import { useQueryGraphStep } from "../../common"
+import { emitEventStep, useQueryGraphStep } from "../../common"
 import { updateCartsStep } from "../steps"
 import { refreshCartItemsWorkflow } from "./refresh-cart-items"
+import { CartWorkflowEvents } from "@medusajs/framework/utils"
 
 /**
  * The cart ownership transfer details.
@@ -110,6 +111,14 @@ export const transferCartCustomerWorkflow = createWorkflow(
         refreshCartItemsWorkflow.runAsStep({
           input: { cart_id: input.id, force_refresh: true },
         })
+
+        emitEventStep({
+          eventName: CartWorkflowEvents.CUSTOMER_TRANSFERRED,
+          data: {
+            id: input.id,
+            customer_id: customer.customer_id,
+          },
+        })
       }
     )
 

packages/core/utils/src/core-flows/events.ts

@@ -48,6 +48,19 @@ export const CartWorkflowEvents = {
    * ```
    */
   REGION_UPDATED: "cart.region_updated",
+
+  /**
+   * Emitted when the customer in the cart is transferred.
+   *
+   * @eventPayload
+   * ```ts
+   * {
+   *   id, // The ID of the cart
+   *   customer_id, // The ID of the customer
+   * }
+   * ```
+   */
+  CUSTOMER_TRANSFERRED: "cart.customer_transferred",
 }
 
 /**