fix: create portal user for customer from shopping cart (#36745)

fix: create portal user  for customer from shopping cart
diff --git a/erpnext/e_commerce/shopping_cart/cart.py b/erpnext/e_commerce/shopping_cart/cart.py
index 4c82393..85d9a65 100644
--- a/erpnext/e_commerce/shopping_cart/cart.py
+++ b/erpnext/e_commerce/shopping_cart/cart.py
@@ -517,6 +517,8 @@
 			}
 		)
 
+		customer.append("portal_users", {"user": user})
+
 		if debtors_account:
 			customer.update({"accounts": [{"company": cart_settings.company, "account": debtors_account}]})