feat: complete internationalization (i18n) for components

Implemented comprehensive i18n translation support for the following components:

1. GitSettings.jsx - Git configuration interface
2. ApiKeysSettings.jsx - API keys settings
3. CredentialsSettings.jsx - Credentials settings (GitHub tokens)
4. TasksSettings.jsx - TaskMaster task management settings
5. ChatInterface.jsx - Chat interface (major translation work)

New translation files:
- src/i18n/locales/en/chat.json - English chat interface translations
- src/i18n/locales/zh-CN/chat.json - Chinese chat interface translations

ChatInterface.jsx translations:
- Code block copy buttons (Copy, Copied, Copy code)
- Message type labels (User, Error, Tool, Claude, Cursor, Codex)
- Tool settings tooltip
- Search result display (pattern, in, results)
- Codex permission modes (Default, Accept Edits, Bypass Permissions, Plan)
- Input placeholder and hint text
- Keyboard shortcut hints (Ctrl+Enter/Enter modes)
- Command menu button

i18n configuration updates:
- Registered chat namespace in config.js
- Extended settings.json translations (git, apiKeys, tasks, agents, mcpServers sections)

完成以下组件的 i18n 翻译工作：

1. GitSettings.jsx - Git 配置界面
2. ApiKeysSettings.jsx - API 密钥设置
3. CredentialsSettings.jsx - 凭据设置（GitHub Token）
4. TasksSettings.jsx - TaskMaster 任务管理设置
5. ChatInterface.jsx - 聊天界面（主要翻译工作）

新增翻译文件：
- src/i18n/locales/en/chat.json - 英文聊天界面翻译
- src/i18n/locales/zh-CN/chat.json - 中文聊天界面翻译

ChatInterface.jsx 翻译内容：
- 代码块复制按钮
- 消息类型标签
- 工具设置提示
- 搜索结果显示
- Codex 权限模式（默认、编辑、无限制、计划模式）
- 输入框占位符和提示文本
- 键盘快捷键提示
- 命令菜单按钮

更新 i18n 配置：
- 在 config.js 中注册 chat 命名空间
- 扩展 settings.json 翻译（git、apiKeys、tasks、agents、mcpServers 等部分）

src/components/GitSettings.jsx

@@ -3,8 +3,10 @@ import { Button } from './ui/button';
 import { Input } from './ui/input';
 import { GitBranch, Check } from 'lucide-react';
 import { authenticatedFetch } from '../utils/api';
+import { useTranslation } from 'react-i18next';
 
 function GitSettings() {
+  const { t } = useTranslation('settings');
   const [gitName, setGitName] = useState('');
   const [gitEmail, setGitEmail] = useState('');
   const [gitConfigLoading, setGitConfigLoading] = useState(false);
@@ -61,17 +63,17 @@ function GitSettings() {
       <div>
         <div className="flex items-center gap-2 mb-4">
           <GitBranch className="h-5 w-5" />
-          <h3 className="text-lg font-semibold">Git Configuration</h3>
+          <h3 className="text-lg font-semibold">{t('git.title')}</h3>
         </div>
 
         <p className="text-sm text-muted-foreground mb-4">
-          Configure your git identity for commits. These settings will be applied globally via <code className="bg-muted px-2 py-0.5 rounded text-xs">git config --global</code>
+          {t('git.description')}
         </p>
 
         <div className="p-4 border rounded-lg bg-card space-y-3">
           <div>
             <label htmlFor="settings-git-name" className="block text-sm font-medium text-foreground mb-2">
-              Git Name
+              {t('git.name.label')}
             </label>
             <Input
               id="settings-git-name"
@@ -83,13 +85,13 @@ function GitSettings() {
               className="w-full"
             />
             <p className="mt-1 text-xs text-muted-foreground">
-              Your name for git commits
+              {t('git.name.help')}
             </p>
           </div>
 
           <div>
             <label htmlFor="settings-git-email" className="block text-sm font-medium text-foreground mb-2">
-              Git Email
+              {t('git.email.label')}
             </label>
             <Input
               id="settings-git-email"
@@ -101,7 +103,7 @@ function GitSettings() {
               className="w-full"
             />
             <p className="mt-1 text-xs text-muted-foreground">
-              Your email for git commits
+              {t('git.email.help')}
             </p>
           </div>
 
@@ -110,13 +112,13 @@ function GitSettings() {
               onClick={saveGitConfig}
               disabled={gitConfigSaving || !gitName || !gitEmail}
             >
-              {gitConfigSaving ? 'Saving...' : 'Save Configuration'}
+              {gitConfigSaving ? t('git.actions.saving') : t('git.actions.save')}
             </Button>
 
             {saveStatus === 'success' && (
               <div className="text-sm text-green-600 dark:text-green-400 flex items-center gap-2">
                 <Check className="w-4 h-4" />
-                Saved successfully
+                {t('git.status.success')}
               </div>
             )}
           </div>