Add TestDriver sample tests for the DreamOS production landing page

[testdriverai]

Set up TestDriver + sample tests (closes #12)

This sets up TestDriver in the repo (vitest + testdriverai, config, and the CI workflow via testdriverai init) and adds a small suite of sample tests that run against the production environment.

What's tested

Target: https://dreamosofficial.github.io/DreamOS/ (the live GitHub Pages site). DreamOS uses Nostr-based auth with a read-only Guest Dreamor mode, so no credentials or fixtures are required for the public surface — the sample tests exercise the deployed landing page:

1. Hero renders — the DreamOS title, the DO IT ALL. ON DREAMOS slogan, and the LAUNCH DREAMOS CTA are visible.
2. Feature highlights — Full OS in Browser, Cherry AI Everywhere, and Accessibility First are shown.
3. Footer links — GitHub and the @dreamOS26 social link are present.

✅ 3/3 passing — full run report

Test	Recording
Hero + launch CTA	replay
Feature highlights	replay
Footer links	replay

⚠️ Heads-up: the interactive app isn't reachable in production

While exploring I found that the LAUNCH DREAMOS button leads to a GitHub Pages 404. It points at https://dreamosofficial.github.io/DreamOS/src/, but src/ only contains raw .jsx source — no built SPA is published there, and GitHub Pages does not honor the _redirects SPA fallback (that's a Cloudflare/Netlify feature). The https://dream-os.pages.dev origin referenced in src/auth/nostr.js currently serves an unrelated Polish-language app, not this DreamOS.

Because of that, the interactive Feed / Discover / Cherry AI flows can't be driven against production yet, so this suite covers the landing page that is live. Once the built app is deployed, these tests can be extended to drive the guest/signed-in Dreamor experience.

Running in CI

The included .github/workflows/testdriver.yml runs these tests. The recommended way to authenticate in CI is the testdriverai/action with GitHub OIDC — no TD_API_KEY secret to store or rotate (one-time: authorize the TestDriver GitHub App for the org at https://console.testdriver.ai). A stored TD_API_KEY secret is only needed as a fallback for runners without OIDC.