refactor(StudyCoursePage): 优化课程详情和目录的空状态显示

- 使用模板统一管理课程详情显示逻辑
- 添加空状态提示组件替代注释掉的代码
- 移除不必要的条件渲染和注释

@@ -40,9 +40,10 @@
                 </div>
                 </div>
             </div>
             </div>
 
 
-            <div v-if="!course?.feature && !course?.highlights && !course?.learning_goal" class="h-2 bg-gray-100"></div>
+            <!-- <div v-if="!course?.feature && !course?.highlights && !course?.learning_goal" class="h-2 bg-gray-100"></div> -->
 
 
-            <div v-if="course?.feature || course?.highlights || course?.learning_goal" id="detail" class="py-4 px-4">
+            <div id="detail" class="py-4 px-4">
+                <template v-if="course?.feature || course?.highlights || course?.learning_goal">
                     <div v-if="course?.feature">
                     <div v-if="course?.feature">
                         <div class="text-black text-xl font-bold mb-2">课程特色</div>
                         <div class="text-black text-xl font-bold mb-2">课程特色</div>
                         <div class="text-gray-700 text-sm leading-relaxed" v-html="course?.feature"></div>
                         <div class="text-gray-700 text-sm leading-relaxed" v-html="course?.feature"></div>
@@ -58,10 +59,12 @@
                         <div class="text-gray-700 text-sm leading-relaxed" v-html="course?.learning_goal"></div>
                         <div class="text-gray-700 text-sm leading-relaxed" v-html="course?.learning_goal"></div>
                         <br />
                         <br />
                     </div>
                     </div>
+                </template>
+                <van-empty v-else description="暂无课程详情" />
             </div>
             </div>
-            <!-- <van-empty v-else description="暂无详情" /> -->
 
 
-            <div v-if="course?.feature || course?.highlights || course?.learning_goal" class="h-2 bg-gray-100"></div>
+            <!-- <div v-if="course?.feature || course?.highlights || course?.learning_goal" class="h-2 bg-gray-100"></div> -->
+            <div class="h-2 bg-gray-100"></div>
 
 
             <div id="catalog" class="py-4">
             <div id="catalog" class="py-4">
                 <div v-if="course_lessons.length" class="space-y-4">
                 <div v-if="course_lessons.length" class="space-y-4">
@@ -79,7 +82,7 @@
                         </div>
                         </div>
                     </div>
                     </div>
                 </div>
                 </div>
-                <!-- <van-empty v-else description="暂无目录" /> -->
+                <van-empty v-else description="暂无课程目录" />
             </div>
             </div>
 
 
             <div v-if="course_lessons.length" class="h-2 bg-gray-100"></div>
             <div v-if="course_lessons.length" class="h-2 bg-gray-100"></div>