重构作业结构：优化实体模型、DTO映射和前端界面

- 重构AppMainStruct、AssignmentQuestion、Question等实体模型
- 更新相关DTO以匹配新的数据结构
- 优化前端页面布局和组件
- 添加全局信息和笔记功能相关代码
- 更新数据库迁移和程序配置

Entities/Contracts/User.cs

@@ -15,8 +15,8 @@ namespace Entities.Contracts
 		public string? RefreshToken { get; set; }
 		public DateTime? RefreshTokenExpiryTime { get; set; }
 		public string? Address { get; set; }	
-		public string? DisplayName { get; set; }	
-
+		public string? DisplayName { get; set; }
+		public SubjectAreaEnum SubjectArea { get; set; } = SubjectAreaEnum.Unknown;
 
 		[Column("deleted")]
 		public bool IsDeleted { get; set; }