refactor: 移除AiHub Domain层对Application.Contracts的循环依赖

移除Yi.Framework.AiHub.Domain项目中对Yi.Framework.AiHub.Application.Contracts的项目引用，解决领域层和应用层之间的循环依赖问题，符合DDD架构分层原则。

Yi.Abp.Net8/module/ai-hub/Yi.Framework.AiHub.Domain/Managers/AiMessageManager.cs

@@ -1,8 +1,8 @@
 using Volo.Abp.Domain.Services;
 using Volo.Abp.Users;
-using Yi.Framework.AiHub.Application.Contracts.Dtos;
 using Yi.Framework.AiHub.Domain.Entities;
 using Yi.Framework.AiHub.Domain.Entities.Chat;
+using Yi.Framework.AiHub.Domain.Shared.Dtos;
 using Yi.Framework.SqlSugarCore.Abstractions;
 
 namespace Yi.Framework.AiHub.Domain.Managers;