fix(teacher): 课程资源为空时禁用展播模式按钮

Made-with: Cursor

reading-platform-frontend/src/views/teacher/lessons/LessonView.vue

@@ -34,7 +34,12 @@
             <StepForwardOutlined />
           </a-button>
         </a-button-group>
-        <a-button type="primary" class="broadcast-btn" @click="openBroadcastMode">
+        <a-button
+          type="primary"
+          class="broadcast-btn"
+          :disabled="!hasCourseResources"
+          @click="openBroadcastMode"
+        >
           <template #icon>
             <ExpandOutlined />
           </template>
@@ -893,8 +898,12 @@ const nextStep = () => {
   }
 };
 
-// 打开展播模式（新标签页）
+// 打开展播模式（新标签页）；无课程级资源时展播无内容，与侧栏「课程资源」一致
 const openBroadcastMode = () => {
+  if (!hasCourseResources.value) {
+    message.warning('暂无课程资源，无法进入展播模式');
+    return;
+  }
   const broadcastUrl = `${window.location.origin}/teacher/broadcast/${lessonId.value}?lessonIndex=${currentLessonIndex.value}&stepIndex=${currentStepIndex.value}`;
   window.open(broadcastUrl, '_blank', 'noopener,noreferrer');
 };