Theme switch support (#3568)

### What problem does this PR solve?
- [x] New Feature (non-breaking change which adds functionality)

---------

Co-authored-by: Yingfeng <yingfeng.zhang@gmail.com>
Co-authored-by: Jin Hai <haijin.chn@gmail.com>

web/src/locales/zh-traditional.ts

@@ -428,6 +428,7 @@ export default {
       multiTurnTip:
         '在多輪對話的中，對去知識庫查詢的問題進行最佳化。會呼叫大模型額外消耗token。',
       howUseId: '如何使用聊天ID？',
+      description: '助理描述',
     },
     setting: {
       profile: '概述',