feat(settings): add option to skip Claude Code first-run confirmation

Add a new setting to automatically skip Claude Code's onboarding screen
by writing hasCompletedOnboarding=true to ~/.claude.json. The setting
defaults to enabled for better user experience.

- Add set/clear_has_completed_onboarding functions in claude_mcp.rs
- Add Tauri commands and frontend API integration
- Add toggle in WindowSettings with i18n support (en/zh/ja)
- Fix hardcoded Chinese text in tests to use i18n keys

src/types.ts

@@ -106,6 +106,8 @@ export interface Settings {
   minimizeToTrayOnClose: boolean;
   // 启用 Claude 插件联动（写入 ~/.claude/config.json 的 primaryApiKey）
   enableClaudePluginIntegration?: boolean;
+  // 跳过 Claude Code 初次安装确认（写入 ~/.claude.json 的 hasCompletedOnboarding）
+  skipClaudeOnboarding?: boolean;
   // 是否开机自启
   launchOnStartup?: boolean;
   // 首选语言（可选，默认中文）