修复考勤管理bug并加强了信息保护

frontend/admin/students.php

@@ -179,7 +179,7 @@ async function loadStudents(page = 1) {
                 <td>${escapeHtml(student.student_no)}</td>
                 <td><a href="/admin/history.php?student_id=${student.student_id}" style="color: #3498db; text-decoration: none;">${escapeHtml(student.name)}</a></td>
                 <td>${student.total_points}</td>
-                ${userRole === '班主任' ? `<td>${student.parent_phone || '-'}</td>` : ''}
+                ${userRole === '班主任' ? `<td>${student.parent_phone ? student.parent_phone.slice(0,3) + '******' + student.parent_phone.slice(-2) : '-'}</td>` : ''}
                 <td>
                     <button class="btn btn-sm btn-primary" onclick="showSinglePointsModal(${student.student_id}, '${escapeHtml(student.name)}')">加减分</button>
                     ${userRole === '班主任' ? `<button class="btn btn-sm btn-secondary" onclick="showEditStudentModal(${student.student_id}, '${escapeHtml(student.student_no)}', '${escapeHtml(student.name)}', '${escapeHtml(student.parent_phone || '')}')">编辑</button>