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/DTO/SubjectTypeMetadataDto.cs

@@ -0,0 +1,14 @@
+using System.ComponentModel.DataAnnotations;
+using System.Collections.Generic;
+using Entities.Contracts;
+
+namespace Entities.DTO
+{
+	public class SubjectTypeMetadataDto
+	{
+		public SubjectAreaEnum SubjectArea { get; set; } = SubjectAreaEnum.Unknown;
+		//public Dictionary<string, (string Color, string DisplayName)> Data = new Dictionary<string, (string Color, string DisplayName)>();
+
+		public string Data = string.Empty;
+	}
+}