nese (zh-CN) localization support

[ziyu121]

添加简体中文本地化支持

Changes

• Added complete zh-CN.json Simplified Chinese translation file
• Replaced all hardcoded English UI text with t() translation function
• Fixed hardcoded English in 70+ files across the codebase
• Auto-detect browser language and switch to Chinese when zh-CN is set
• Added I18nProvider client component for Next.js App Router compatibility
• Installed i18next, react-i18next, i18next-browser-languagedetector

Scope

• Sidebar navigation, Home, Settings, Tasks, Protocols, Activity
• Connectors, Skills, Quality, MCP Servers
• All layout.tsx files
• Shared components (Command Palette, Search, Keyboard Shortcuts, Confirm Dialog, etc.)

Testing

• npm run dev runs without errors
• All UI text displays correctly in Chinese
• English fallback (en.json) works properly when needed

Technical Details

• Uses i18next + react-i18next framework

• Translation files located at src/i18n/locales/

• All text loaded via t('key') function calls
  Notes

• en.json remains as the fallback language

• Users with zh-CN browser language will see Chinese automatically

  Extensibility
  This PR sets up a fully functional i18n infrastructure that makes adding new languages straightforward:

-Adding a new language** only requires:

1. Copying en.json to a new locale file (e.g., fr.json, es.json, ja.json)
2. Translating the values
3. Adding the locale to the resources object in src/i18n/index.ts
4. The language detector will automatically switch based on browser settings

-No code changes** needed in UI components when adding new languages

• All text is centralized in JSON files, making translation management easy

• 修改内容

• 新增完整的 zh-CN.json 简体中文翻译文件

• 所有界面文本已替换为 t() 翻译函数

• 修正 70+ 个文件中的硬编码英文文本

• 支持浏览器语言自动检测 (zh-CN)

• 新增 I18nProvider 客户端组件，兼容 Next.js App Router

涉及范围
侧边栏、首页、设置、任务、协议、动态

• 连接器、技能、质量、MCP 服务器
• 所有 layout 文件
• 通用组件（命令面板、搜索、快捷键、确认对话框等）

测试

• npm run dev 正常运行，无编译错误
• 所有界面正常显示中文
• 英文回退 (en.json) 正常工作

技术实现

• 使用 i18next + react-i18next 框架
• 新增 src/i18n/ 目录管理翻译文件
• 所有文本通过 t('key') 方式加载