修正学习会话计时指针与时间单位定义

src/main/java/com/guo/learningprogresstracker/dto/response/StudySessionResponse.java

@@ -28,11 +28,11 @@ public class StudySessionResponse {
     private LocalDateTime endTime;
 
 
-    @Schema(description = "实际使用时间（分钟）")
+    @Schema(description = "实际使用时间（秒）")
     private double actualTime;
 
 
-    @Schema(description = "有效学习时间（分钟）")
+    @Schema(description = "有效学习时间（秒）")
     private double effectiveTime;
 
 
@@ -43,7 +43,7 @@ public class StudySessionResponse {
     @Schema(description = "学习会话的状态（进行中、暂停、已结束）")
     private String sessionState;
 
-    @Schema(description = "倒计时开始位置（S）")
+    @Schema(description = "倒计时指针位置（毫秒）")
     private double pointerPosition;
 
     @Schema(description = "系统提示")