feat(课程学习): 添加课程详情页和课程学习页的滚动位置同步功能

在课程详情页跳转至学习页时传递课程ID，并在学习页中监听课程ID变化时同步滚动位置

@@ -125,6 +125,9 @@ import CheckInDialog from '@/components/checkin/CheckInDialog.vue';
 import { getCourseDetailAPI } from '@/api/course';
 
 const router = useRouter();
+const course_id = computed(() => {
+    return router.currentRoute.value.params.id || '';
+});
 
 // 页面标题
 useTitle('课程详情');
@@ -265,8 +268,7 @@ const timeout_task_list = ref([]);
  */
 
 const get_scroll_store_key = () => {
-    const course_id = router.currentRoute.value.params.id || '';
-    return `study_course_scroll_${course_id}`;
+    return `study_course_scroll_${course_id.value}`;
 };
 
 /**
@@ -485,7 +487,7 @@ const handleTabChange = (name) => {
 
 const goToStudyDetail = (lessonId) => {
     save_scroll_state(lessonId);
-    router.push(`/studyDetail/${lessonId}`);
+    router.push({ path: `/studyDetail/${lessonId}`, query: { from_course_id: course_id.value } });
 };
 
 // 打卡相关状态

@@ -426,9 +426,51 @@ const handleScroll = () => {
 
 const courseFile = ref({});
 
+/**
+ * @function sync_study_course_back_position
+ * @description 同步学习课程返回位置
+ * @param {string} lesson_id - 当前课程目录项ID
+ * @returns {void}
+ * 注释：在用户点击目录项时调用，记录当前滚动位置和目录项ID
+ */
+
+const sync_study_course_back_position = (lesson_id) => {
+    const from_course_id = route.query.from_course_id || '';
+    if (!from_course_id) return;
+
+    const key = `study_course_scroll_${from_course_id}`;
+    const raw = sessionStorage.getItem(key);
+
+    let payload = null;
+    try {
+        payload = raw ? JSON.parse(raw) : null;
+    } catch (e) {
+        payload = null;
+    }
+
+    if (!payload || typeof payload !== 'object') {
+        payload = { scroll_y: 0, lesson_id: '', saved_at: 0 };
+    }
+
+    payload.lesson_id = lesson_id || payload.lesson_id || '';
+    payload.saved_at = Date.now();
+
+    sessionStorage.setItem(key, JSON.stringify(payload));
+};
+
+watch(
+    () => route.params.id,
+    (val) => {
+        sync_study_course_back_position(val || '');
+    },
+    { immediate: true }
+);
+
 const handleLessonClick = async (lesson) => {
     showCatalog.value = false; // 关闭目录弹窗
     isPlaying.value = false; // 重置播放状态
+    // 同步学习课程返回位置
+    sync_study_course_back_position(lesson.id);
 
     // 更新URL地址，不触发页面重新加载
     router.replace({ params: { id: lesson.id } });