fix(后端)：@Transactional + WebMvcProdConfig OPTIONS 跳过

- WebMvcProdConfig：SaInterceptor 增加 OPTIONS 预检跳过，
  解决生产环境 CORS 预检 401 问题
- StudySessionsServiceImpl.endedStudySession/continueStudySession：
  增加 @Transactional
- StudyReportFragmentsServiceImpl.createFragments：
  增加 @Transactional

src/main/java/com/guo/learningprogresstracker/service/impl/StudySessionsServiceImpl.java

@@ -21,6 +21,7 @@ import com.guo.learningprogresstracker.service.StudySessionsService;
 import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
 import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
 
 import java.time.LocalDateTime;
 import java.util.ArrayList;
@@ -96,6 +97,7 @@ public class StudySessionsServiceImpl extends ServiceImpl<StudySessionsMapper, S
 
 
     @Override
+    @Transactional
     public String endedStudySession(String sessionNum, String content) throws ErrorParameterException {
         StudySessionsEntity studySessionsEntity = this.getOneOpt(Wrappers.lambdaQuery(StudySessionsEntity.class)
                         .eq(StudySessionsEntity::getSessionNum, sessionNum))
@@ -136,6 +138,7 @@ public class StudySessionsServiceImpl extends ServiceImpl<StudySessionsMapper, S
     }
 
     @Override
+    @Transactional
     public void continueStudySession(String sessionNum) throws ErrorParameterException, ServiceException {
         StudySessionsEntity studySessionsEntity = this.getOneOpt(Wrappers.lambdaQuery(StudySessionsEntity.class)
                         .eq(StudySessionsEntity::getSessionNum, sessionNum))