[good first issue] Add keyboard navigation test for the Contact form

[kevinccbsg]

Real-world a11y expectation. Exercises userEvent.tab() together with the existing be.focused assertion.

Scope

• New test file examples/twd-test-app/src/twd-tests/contact-keyboard.twd.test.ts:
  • Visit /contact.
  • Query every field with screenDom.getByLabelText(...).
  • Call userEvent.tab() repeatedly; after each Tab, assert the expected field with twd.should(el, "be.focused").
  • Confirm Shift+Tab reverses the focus order.
  • Confirm that pressing Enter on the last field submits the form (or moves focus to the submit button).
• If the Contact page is missing proper labels for getByLabelText, add them — avoid relying on CSS selectors.

Reference

• examples/twd-test-app/src/twd-tests/screen-queries.twd.test.ts for screenDom usage.
• examples/twd-test-app/src/twd-tests/assertion-examples.twd.test.ts for be.focused.

Acceptance criteria

• All test cases run green in the TWD sidebar.
• PR includes a sidebar screenshot.
• Optional: one-line recipe in docs/writing-tests.md.

How to contribute

Read CONTRIBUTING.md first. Quick steps for this issue:

1. Fork, clone, create a feature branch: git checkout -b feat/contact-keyboard-test.
2. From the repo root, build the library and sync it to the example apps:

   npm install
   npm run build
   npm run copy:mock-sw

3. Install and run the test app:

   cd examples/twd-test-app
   npm install
   npm run dev

4. Open the app in the browser — the TWD sidebar appears on the right. Run your new tests from the sidebar and confirm they pass.
5. Run the library's unit tests from the repo root: npm run test:ci.
6. Open the PR with screenshots of the sidebar showing green tests.

Always prefer screenDom (Testing Library) for element queries. Avoid twd.get() in new code.