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-tauri/src/lib.rs

@@ -585,6 +585,8 @@ pub fn run() {
             commands::read_claude_plugin_config,
             commands::apply_claude_plugin_config,
             commands::is_claude_plugin_applied,
+            commands::apply_claude_onboarding_skip,
+            commands::clear_claude_onboarding_skip,
             // Claude MCP management
             commands::get_claude_mcp_status,
             commands::read_claude_mcp_config,