AI自主学习生成课程提示词拼接bug修复（每节课都一样的问题）

src/components/study/SelfDirectedLearning.vue

@@ -331,7 +331,12 @@ const generateScript = async () => {
     for (let i = 0; i < lessonList.value.length; i++) {
       let lesson = lessonList.value[i]
       progressSteps.value[1].text = "生成课程小节【" + lesson.name + "】..."
-      content = i === 0 ? content + `现在开始生成第${i+1}节课：${lesson.name}` : content
+      let nameTemp = `现在开始生成第${i+1}节课：${lesson.name}`
+      if(i === 0){
+        content += nameTemp
+      }else{
+        content = nameTemp
+      }
       let lessonInfo = {courseName: lesson.name, courseLabel: lesson.id};
       await doSendMessageStream(activeConversationId.value, content, lessonInfo)
       console.log("生成课程小节信息：", lessonInfo)