增加Mediat Pip特性，并用实例来做一个demo

Modules/Store.Users/Behaviors/ConsumptionContracts.cs

@@ -0,0 +1,23 @@
+using Store.Users.Entities;
+using YourNamespace;
+
+namespace Store.Users.Behaviors;
+
+/// <summary>需要账户积分消费检查的请求。</summary>
+public interface IAccountConsumptionRequest
+{
+    string UserName { get; }
+    AccountConsumptionContext? ConsumptionContext { get; set; }
+    ConsumptionQuote CalculateConsumption(UserEntity user);
+}
+
+/// <summary>需要检查商铺归属的请求，与是否消费无关。</summary>
+public interface IShopOwnershipRequest
+{
+    string UserName { get; }
+    string ShopId { get; }
+    ShopEntity? OwnedShop { get; set; }
+}
+
+public sealed record ConsumptionQuote(decimal Amount, decimal UnitPrice);
+public sealed record AccountConsumptionContext(UserEntity User, ConsumptionQuote Quote);