feat：重构倒计时相关内容，将倒计时逻辑放在后端进行

src/main/java/com/guo/learningprogresstracker/controller/StudySessionController.java

@@ -1,6 +1,7 @@
 package com.guo.learningprogresstracker.controller;
 
 import com.baomidou.mybatisplus.core.toolkit.Wrappers;
+import com.google.protobuf.ServiceException;
 import com.guo.learningprogresstracker.dto.request.EndedStudySessionRequest;
 import com.guo.learningprogresstracker.dto.response.StudySessionResponse;
 import com.guo.learningprogresstracker.entity.CommonResult;
@@ -49,7 +50,7 @@ public class StudySessionController {
      * 开始一个【学习会话】
      */
     @PostMapping("/{sessionNum}/study-sessions/continue")
-    public CommonResult<Void> startStudySession(@PathVariable("sessionNum") String sessionNum) throws ErrorParameterException {
+    public CommonResult<Void> startStudySession(@PathVariable("sessionNum") String sessionNum) throws ErrorParameterException, ServiceException {
         studySessionsServiceImpl.continueStudySession(sessionNum);
         return CommonResult.success();
     }
@@ -58,8 +59,10 @@ public class StudySessionController {
      * 暂停一个【学习会话】
      */
     @PostMapping("/{sessionNum}/study-sessions/pause")
-    public CommonResult<Void> pauseStudySession(@PathVariable("sessionNum") String sessionNum, @RequestParam(value = "endTime",required = false) LocalDateTime endTime) throws ErrorParameterException {
-        studySessionsServiceImpl.pauseStudySession(sessionNum,endTime);
+    public CommonResult<Void> pauseStudySession(@PathVariable("sessionNum") String sessionNum,
+                                                @RequestParam(value = "endTime", required = false) LocalDateTime endTime)
+            throws ErrorParameterException, ServiceException {
+        studySessionsServiceImpl.pauseStudySession(sessionNum, endTime);
         return CommonResult.success();
     }