fix: restore the workspace brand subtitle

The primary sidebar showed only the GoodBuddy name after its supporting brand line was removed. It now displays the localized “智能工作台” / “Intelligent Workspace” subtitle beneath the product name again.

Release note: 恢复左上角 GoodBuddy 标题下方的“智能工作台”副标题，使品牌区域的信息层级更加完整。

src/renderer/src/App.test.tsx

@@ -1336,7 +1336,7 @@ describe('App', () => {
         /你好，我是 GoodBuddy。你可以直接向我提问、添加本地文件/u
       )
     ).toBeInTheDocument()
-    expect(screen.queryByText('桌面工作区')).not.toBeInTheDocument()
+    expect(screen.getByText('智能工作台')).toBeInTheDocument()
     expect(screen.queryByText('GOODBUDDY 工作台')).not.toBeInTheDocument()
     expect(
       document.querySelector('.composer__runtime-toolbar')

src/renderer/src/App.tsx

@@ -7916,6 +7916,7 @@ function App(): React.JSX.Element {
           </div>
           <div className="brand__copy">
             <strong>GoodBuddy</strong>
+            <span>{t('brand.subtitle')}</span>
           </div>
         </div>
 

src/renderer/src/i18n/locales/en-US/app.ts

@@ -2,6 +2,9 @@ import type { TranslationShape } from '../../resource-types'
 import type { app as chineseApp } from '../zh-CN/app'
 
 export const app = {
+  brand: {
+    subtitle: 'Intelligent Workspace'
+  },
   notifications: {
     success: 'Success',
     error: 'Error',

src/renderer/src/i18n/locales/zh-CN/app.ts

@@ -1,4 +1,7 @@
 export const app = {
+  brand: {
+    subtitle: '智能工作台'
+  },
   notifications: {
     success: '成功',
     error: '错误',