feat: update StartTask component and add documentation

src/components/StartTask.vue

@@ -7,6 +7,7 @@ import { useTimer } from "@/components/composables/useTimer";
 import {
   continueSession,
   endSession,
+  getSessionDetail,
   pauseSession,
   startOrContinueStudySession,
 } from "@/api/studySessions";
@@ -269,7 +270,10 @@ const toDate = (value: unknown): Date | null => {
   }
 
   if (typeof value === "string") {
-    const normalized = value.includes("T") ? value : value.replace(" ", "T");
+    // 去掉末尾的 'Z'：后端 LocalDateTime 无时区，序列化时不应带 Z
+    // （旧版序列化器曾错误添加字面量 Z，此处做兼容处理）
+    const clean = value.endsWith("Z") ? value.slice(0, -1) : value;
+    const normalized = clean.includes("T") ? clean : clean.replace(" ", "T");
     const date = new Date(normalized);
     return Number.isNaN(date.getTime()) ? null : date;
   }
@@ -338,7 +342,23 @@ const stopTimer = async () => {
   const res = await pauseSession(taskInfo.value.sessionNum);
   if (res.code === 200) {
     ElMessage.success("任务暂停");
-    taskInfo.value.sessionState = "PAUSED";
+    // 重新获取会话数据，同步后端计算后的时间字段
+    try {
+      const detail = await getSessionDetail(taskInfo.value.sessionNum);
+      if (detail?.data) {
+        const d = detail.data;
+        taskInfo.value.sessionState = d.sessionState ?? "PAUSED";
+        taskInfo.value.actualTime = d.actualTime ?? 0;
+        taskInfo.value.effectiveTime = d.effectiveTime ?? 0;
+        taskInfo.value.effectivenessRatio = d.effectivenessRatio ?? 0;
+        taskInfo.value.startTime = d.startTime ?? taskInfo.value.startTime;
+        taskInfo.value.endTime = d.endTime ?? "";
+        taskInfo.value.lastStartTime = d.lastStartTime ?? "";
+        taskInfo.value.pointerPosition = d.pointerPosition ?? 0;
+      }
+    } catch {
+      taskInfo.value.sessionState = "PAUSED";
+    }
   }
   clear();
   clearBreakState();