fix：修复发送框问题

dashboard/src/views/ConversationView.vue

@@ -218,9 +218,10 @@ const renderMsgContent = (msg) => {
 // 处理发送消息
 const handleSend = async () => {
   if (!newMessage.value.trim()) return
-  await sendMessage(newMessage.value)
-  newMessage.value = ''
+  const message = newMessage.value.trim()
+  newMessage.value = ''  // 先清空输入框，再发送
   scrollToBottom()
+  await sendMessage(message)
 }
 
 // 处理创建会话