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

tests/components/ImportExportSection.test.tsx

@@ -63,7 +63,7 @@ describe("ImportExportSection Component", () => {
     fireEvent.click(importButton);
     expect(baseProps.onImport).toHaveBeenCalledTimes(1);
 
-    fireEvent.click(screen.getByRole("button", { name: "Clear selection" }));
+    fireEvent.click(screen.getByRole("button", { name: "common.clear" }));
     expect(baseProps.onClear).toHaveBeenCalledTimes(1);
   });