Fix compilation error in TestController

Change order.Total to order.TotalAmount to match model property.

Co-Authored-By: Claude <noreply@anthropic.com>

LittleShop/Controllers/TestController.cs

@@ -199,7 +199,7 @@ public class TestController : ControllerBase
                     id = o.Id,
                     identityReference = o.IdentityReference,
                     createdAt = o.CreatedAt,
-                    total = o.Total
+                    total = o.TotalAmount
                 })
             });
         }