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

TechHelper.Client/Pages/Common/Exam/AssignmentInfoCard.razor

@@ -2,7 +2,7 @@
 
 	<MudGrid Class="h-100">
 
-		<MudItem xs="12" sm="2" Class="h-100 pa-1 mt-1">
+		<MudItem sm="2" Class="h-100 pa-1 mt-1">
 			<MudStack Class="h-100">
 				<MudText Style="color:white"> BETA版本 </MudText>
 				<MudText Style="color:white" Typo="Typo.h3"><b> 75  </b></MudText>
@@ -44,7 +44,7 @@
 		</MudItem>
 
 
-		<MudItem xs="12" sm="9">
+		<MudItem sm="9">
 			<MudPaper Style="background-color:transparent" Class="w-100 mt-n3" Height="100%" Elevation="0">
 				<MudChart ChartType="ChartType.Line" Class="pt-0" ChartSeries="@Series" XAxisLabels="@XAxisLabels" CanHideSeries
 						  Height="150px" Width="100%" AxisChartOptions="_axisChartOptions" ChartOptions="options">
@@ -72,12 +72,6 @@
 	</MudGrid>
 </MudPaper>
 
-@* 				<MudChip Size="Size.Small" Text="pink" Variant="Variant.Text" Color="Color.Secondary">成绩趋势</MudChip>
-				<MudChip Size="Size.Small" Text="blue" Variant="Variant.Text" Color="Color.Info">分值区间</MudChip>
-				<MudChip Size="Size.Small" Text="green" Variant="Variant.Text" Color="Color.Success">Success</MudChip>
-				<MudChip Size="Size.Small" Text="orange" Variant="Variant.Text" Color="Color.Warning">Warning</MudChip>
-				<MudChip Size="Size.Small" Text="red" Variant="Variant.Text" Color="Color.Error">Error</MudChip>
-				<MudChip Size="Size.Small" Text="black" Variant="Variant.Text" Color="Color.Dark">Dark</MudChip> *@
 
 @code {
 	public double[] data = { 25, 77, 28, 5 };