feat(学生): 添加成绩分析功能及密码修改功能

- 新增成绩分析页面，包含GPA趋势图、成绩分布图和学分进度
- 实现学生密码修改功能，包括前端表单和后端验证逻辑
- 添加课程类别分析功能，展示不同类别课程的GPA表现
- 优化学生仪表板和课程页面导航链接
- 增加数据加载状态提示和错误处理

frontend/views/student/profile.html

@@ -201,13 +201,13 @@
                 </a>
             </div>
             <div class="nav-item">
-                <a href="/student/dashboard#stats-section" class="nav-link">
+                <a href="/student/grade-analysis" class="nav-link">
                     <i class="fas fa-chart-line"></i>
                     <span>成绩分析</span>
                 </a>
             </div>
             <div class="nav-item">
-                <a href="#" class="nav-link active">
+                <a href="/student/profile" class="nav-link active">
                     <i class="fas fa-user"></i>
                     <span>个人中心</span>
                 </a>
@@ -285,21 +285,21 @@
                             
                             <div class="mb-3">
                                 <label class="form-label">原密码</label>
-                                <input type="password" class="form-control" placeholder="请输入原密码">
+                                <input type="password" class="form-control" id="oldPassword" placeholder="请输入原密码">
                             </div>
                             <div class="row mb-4">
                                 <div class="col-md-6">
                                     <label class="form-label">新密码</label>
-                                    <input type="password" class="form-control" placeholder="请输入新密码">
+                                    <input type="password" class="form-control" id="newPassword" placeholder="请输入新密码">
                                 </div>
                                 <div class="col-md-6">
                                     <label class="form-label">确认新密码</label>
-                                    <input type="password" class="form-control" placeholder="再次输入新密码">
+                                    <input type="password" class="form-control" id="confirmPassword" placeholder="再次输入新密码">
                                 </div>
                             </div>
                             
                             <div class="text-end">
-                                <button type="button" class="btn btn-primary px-4" onclick="alert('修改密码功能暂未开放')">
+                                <button type="button" class="btn btn-primary px-4" id="savePasswordBtn">
                                     <i class="fas fa-save me-1"></i> 保存更改
                                 </button>
                             </div>
@@ -341,6 +341,56 @@
             };
             updateTime();
             setInterval(updateTime, 1000);
+
+            // 修改密码逻辑
+            const savePasswordBtn = document.getElementById('savePasswordBtn');
+            if (savePasswordBtn) {
+                savePasswordBtn.addEventListener('click', async () => {
+                    const oldPassword = document.getElementById('oldPassword').value;
+                    const newPassword = document.getElementById('newPassword').value;
+                    const confirmPassword = document.getElementById('confirmPassword').value;
+
+                    if (!oldPassword || !newPassword || !confirmPassword) {
+                        alert('请填写所有密码字段');
+                        return;
+                    }
+
+                    if (newPassword !== confirmPassword) {
+                        alert('两次输入的新密码不一致');
+                        return;
+                    }
+
+                    if (newPassword.length < 6) {
+                        alert('新密码长度至少为 6 位');
+                        return;
+                    }
+
+                    try {
+                        const response = await fetch('/api/auth/update-password', {
+                            method: 'PUT',
+                            headers: {
+                                'Content-Type': 'application/json'
+                            },
+                            body: JSON.stringify({ oldPassword, newPassword })
+                        });
+
+                        const result = await response.json();
+                        if (result.success) {
+                            alert('密码修改成功，请重新登录');
+                            // 登出并跳转到登录页
+                            fetch('/api/auth/logout', { method: 'POST' })
+                                .then(() => {
+                                    window.location.href = '/login';
+                                });
+                        } else {
+                            alert(result.message || '修改失败');
+                        }
+                    } catch (error) {
+                        console.error('Update password error:', error);
+                        alert('网络错误，请稍后再试');
+                    }
+                });
+            }
         });
     </script>
 </body>