add:教师端新增删除课程，增加并更换footer-brief模板

Html/apps/templates/teacherboard.html

@@ -65,7 +65,7 @@
             </div>
         </ul>
         <button class="add-chapter-btn" onclick="showInputForNewChapter()">新增章节</button>
-        
+        <button class="delete-course-btn" onclick="showDeleteCourseConfirmation()">删除课程</button>
     </div>
 
     <!-- 编辑章节或课时弹窗 -->
@@ -121,6 +121,6 @@
     <script src="/static/js/course_current.js"></script>
     <script src="/static/js/teacherboard.js"></script>
     <script src="/static/js/teacher_course_setting.js"></script>
-     {% include 'foot.html' %}
+     {% include 'footer-brief.html' %}
 </body>
 </html>