feat(课程详情页): 添加课程大纲展开/收起功能

为了优化用户体验，当课程大纲条目超过4条时，默认显示前4条，并提供展开/收起按钮，点击按钮可查看全部或收起部分条目

@@ -78,10 +78,15 @@
 
             <div v-if="activeTab === '课程大纲'">
               <div class="space-y-4">
-                <div v-for="(item, index) in course?.schedule" :key="index" class="border-l-2 border-green-500 pl-3">
+                <div v-for="(item, index) in displayedSchedule" :key="index" class="border-l-2 border-green-500 pl-3">
                   <h4 class="font-medium text-gray-800">{{ item.title }}</h4>
                   <p class="text-sm text-gray-600 mt-1">{{ item.duration }}分钟 · {{ item.schedule_time || '空数据' }}个小节</p>
                 </div>
+                <div v-if="course?.schedule?.length > 4" class="flex justify-center mt-4">
+                  <button @click="toggleSchedule" class="p-2 rounded-full hover:bg-green-50 text-green-600 hover:text-green-700 transition-all duration-300">
+                    <van-icon :name="isScheduleExpanded ? 'arrow-down' : 'arrow-up'" class="text-xl transform transition-transform duration-300" />
+                  </button>
+                </div>
               </div>
             </div>
 
@@ -399,6 +404,22 @@ onMounted(async () => {
     }
   }
 })
+
+
+const isScheduleExpanded = ref(false)
+
+// 计算显示的课程大纲列表
+const displayedSchedule = computed(() => {
+  if (!course.value?.schedule) return []
+  return isScheduleExpanded.value || course.value.schedule.length <= 4
+    ? course.value.schedule
+    : course.value.schedule.slice(0, 4)
+})
+
+// 切换课程大纲展开/收起状态
+const toggleSchedule = () => {
+  isScheduleExpanded.value = !isScheduleExpanded.value
+}
 </script>
 
 <style scoped>