feat(学生): 添加学生课程管理功能

- 新增我的课程页面及路由
- 实现课程列表和详情查看功能
- 更新导航链接指向新页面
- 添加成绩详情模态框
- 完善相关后端接口和服务

backend/server.js

@@ -96,6 +96,9 @@ app.get('/dashboard', requirePageAuth, (req, res) => {
 app.get('/student/dashboard', requirePageAuth, requirePageRole(['student']), (req, res) => {
     res.sendFile(path.join(__dirname, '../frontend/views/student/dashboard.html'));
 });
+app.get('/student/my-courses', requirePageAuth, requirePageRole(['student']), (req, res) => {
+    res.sendFile(path.join(__dirname, '../frontend/views/student/my_courses.html'));
+});
 app.get('/student/profile', requirePageAuth, requirePageRole(['student']), (req, res) => {
     res.sendFile(path.join(__dirname, '../frontend/views/student/profile.html'));
 });