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/AppMainStruct.cs

@@ -1,6 +1,8 @@
 using System;
 using System.Collections.Generic;
+using System.ComponentModel.DataAnnotations;
 using System.Linq;
+using System.Reflection;
 using System.Text;
 using System.Threading.Tasks;
 
@@ -34,9 +36,11 @@ namespace Entities.Contracts
 
 	public enum DifficultyLevel : byte
 	{
+		simple,
 		easy,
 		medium,
-		hard
+		hard,
+		veryHard
 	}
 
 	public enum QuestionType : byte
@@ -55,47 +59,131 @@ namespace Entities.Contracts
 
 	public enum SubjectAreaEnum : byte
 	{
-		Unknown = 0,         
-		Mathematics,     // 数学
-		Physics,         // 物理
-		Chemistry,       // 化学
-		Biology,         // 生物
-		History,         // 历史
-		Geography,       // 地理
+		[Display(Name = "未知", Description = "未知")]
+		Unknown = 0,
+
+		[Display(Name = "数学", Description = "数")]
+		Mathematics,      // 数学
+
+		[Display(Name = "物理", Description = "物")]
+		Physics,          // 物理
+
+		[Display(Name = "化学", Description = "化")]
+		Chemistry,        // 化学
+
+		[Display(Name = "生物", Description = "生")]
+		Biology,          // 生物
+
+		[Display(Name = "历史", Description = "史")]
+		History,          // 历史
+
+		[Display(Name = "地理", Description = "地")]
+		Geography,        // 地理
+
+		[Display(Name = "语文", Description = "语")]
 		Literature,      // 语文/文学
-		English,         // 英语
-		ComputerScience, // 计算机科学
+
+		[Display(Name = "英语", Description = "英")]
+		English,          // 英语
+
+		[Display(Name = "计算机科学", Description = "计")]
+		ComputerScience // 计算机科学
 	}
 
 	public enum AssignmentStructType : byte
 	{
+		[Display(Name = "根节点", Description = "根")]
 		Root,
+		[Display(Name = "单个问题", Description = "问")]
 		Question,
+		[Display(Name = "问题组", Description = "组")]
 		Group,
+		[Display(Name = "结构", Description = "结")]
 		Struct,
+		[Display(Name = "子问题", Description = "子")]
 		SubQuestion,
+		[Display(Name = "选项", Description = "选")]
 		Option
 	}
 
-
 	public enum ExamType : byte
 	{
-		MidtermExam,       // 期中
-		FinalExam,         // 期末
-		MonthlyExam,       // 月考
-		WeeklyExam,        // 周考
-		DailyTest,         // 平时测试
-		AITest,            // AI测试
-	}
+		[Display(Name = "期中考试", Description = "中")]
+		MidtermExam,
 
+		[Display(Name = "期末考试", Description = "末")]
+		FinalExam,
+
+		[Display(Name = "月考", Description = "月")]
+		MonthlyExam,
+
+		[Display(Name = "周考", Description = "周")]
+		WeeklyExam,
+
+		[Display(Name = "平时测试", Description = "平")]
+		DailyTest,
+
+		[Display(Name = "AI测试", Description = "AI")]
+		AITest,
+	}
 
 	public enum SubmissionStatus
 	{
-		Pending,        // 待提交/未开始
-		Submitted,      // 已提交
-		Graded,         // 已批改
-		Resubmission,   // 待重新提交 (如果允许)
-		Late,           // 迟交
-		Draft,          // 草稿
+		[Display(Name = "待提交/未开始", Description = "待")]
+		Pending,
+
+		[Display(Name = "已提交", Description = "提")]
+		Submitted,
+
+		[Display(Name = "已批改", Description = "批")]
+		Graded,
+
+		[Display(Name = "待重新提交", Description = "重")]
+		Resubmission,
+
+		[Display(Name = "迟交", Description = "迟")]
+		Late,
+
+		[Display(Name = "草稿", Description = "草")]
+		Draft,
+	}
+
+	public static class EnumExtensions
+	{
+		public static string GetDisplayName(this Enum enumValue)
+		{
+			var fieldInfo = enumValue.GetType().GetField(enumValue.ToString());
+
+			if (fieldInfo == null)
+			{
+				return enumValue.ToString(); 
+			}
+
+			var displayAttribute = fieldInfo.GetCustomAttribute<DisplayAttribute>();
+
+			if (displayAttribute != null)
+			{
+				return displayAttribute.Name;
+			}
+
+			return enumValue.ToString();
+		}
+
+		public static string GetShortName(this Enum enumValue)
+		{
+			var memberInfo = enumValue.GetType().GetMember(enumValue.ToString()).FirstOrDefault();
+
+			if (memberInfo != null)
+			{
+				var displayAttribute = memberInfo.GetCustomAttribute<DisplayAttribute>();
+
+				if (displayAttribute != null && !string.IsNullOrEmpty(displayAttribute.Description))
+				{
+					return displayAttribute.Description;
+				}
+			}
+
+			return enumValue.ToString();
+		}
 	}
 }