feat: 添加学生提交系统功能

- 添加学生提交管理服务 (StudentSubmissionService, StudentSubmissionDetailService)
- 新增学生提交相关控制器 (StudentSubmissionController, StudentSubmissionDetailController)
- 添加学生提交数据传输对象 (StudentSubmissionDetailDto, StudentSubmissionSummaryDto)
- 新增学生提交相关页面组件 (StudentExamView, ExamDetailView, StudentCard等)
- 添加学生提交信息卡片组件 (SubmissionInfoCard, TeacherSubmissionInfoCard)
- 更新数据库迁移文件以支持提交系统

Entities/Contracts/AssignmentQuestion.cs

@@ -48,6 +48,8 @@ namespace Entities.Contracts
 		[Column("score")]
 		public float? Score { get; set; }
 
+		public bool BCorrect { get; set; }
+
 		[Column("deleted")]
 		public bool IsDeleted { get; set; }