fix: restore reproducible frontend builds

digital-avatar-app/src/views/AvatarChat.vue

@@ -116,12 +116,13 @@ const avatarStatus = computed(() => {
   return { tone: 'active', label: '在线，随时可以和我聊聊' }
 })
 
-const sourceLabel = (source?: DisplayMessage['source']) => ({
+const sourceLabels: Record<NonNullable<DisplayMessage['source']>, string> = {
   qa: '标准问答对',
   knowledge: '参考文件知识库',
   qwen: '智能回答',
   public: ''
-}[source || ''] || '')
+}
+const sourceLabel = (source?: DisplayMessage['source']) => source ? sourceLabels[source] : ''
 
 const scrollToBottom = async () => {
   await nextTick()