重构项目结构，移除Assignment相关功能，优化Submission模块

Entities/Contracts/AppMainStruct.cs

@@ -43,18 +43,11 @@ namespace Entities.Contracts
 		veryHard
 	}
 
-	public enum QuestionType : byte
+	public enum TypeNameType : byte
 	{
-		Unknown = 0,
-		Spelling,           // 拼写
-		Pronunciation,      // 给带点字选择正确读音
-		WordFormation,      // 组词
-		FillInTheBlanks,    // 选词填空 / 补充词语
-		SentenceDictation,  // 默写句子
-		SentenceRewriting,  // 仿句 / 改写句子
-		ReadingComprehension, // 阅读理解
-		Composition         // 作文
-							
+		Subject = 0,
+		QuestionType = 1,
+		ExamType = 2,
 	}
 
 	public enum SubjectAreaEnum : byte
@@ -90,7 +83,7 @@ namespace Entities.Contracts
 		ComputerScience // 计算机科学
 	}
 
-	public enum AssignmentStructType : byte
+	public enum ExamStructType : byte
 	{
 		[Display(Name = "根节点", Description = "根")]
 		Root,
@@ -105,26 +98,12 @@ namespace Entities.Contracts
 		[Display(Name = "选项", Description = "选")]
 		Option
 	}
-
-	public enum ExamType : byte
+	
+	public enum UserRoles
 	{
-		[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,
+		Student,
+		Teacher,
+		Admin
 	}
 
 	public enum SubmissionStatus