Closes #20.

What was done

• New e2e/ workspace (@t19/e2e) with Playwright and @axe-core/playwright. Root script pnpm test:e2e; the base URL comes from E2E_BASE_URL (default http://localhost:5173/project2/). pnpm test does not run it, so CI is unchanged.
• e2e/tests/search.spec.ts:
  • Journey: search "beatles" → filter 1960s → sort Z–A and A–Z → open Abbey Road → publish a 4-star review → reload and the review is still there → back to discovery keeps q, decade and sort from the URL → delete the review so runs leave the database as it was.
  • Case-insensitivity: ABBEY and abbey give the same results.
  • Keyboard only: Tab to the skip link, Enter, Tab to the search box, type and Enter, Tab to the result (focus ring visible), Enter opens the album.
• e2e/tests/a11y.spec.ts: axe-core scans (WCAG 2.1 A + AA) of the start page, results with filters open, empty results and the album detail page. Runs in a real browser, so colour contrast is included, unlike the jsdom tests.
• README, AGENTS.md and AI-USAGE.md updated.

The tests expect the db:seed catalog. The VM's MusicBrainz catalog has no Abbey Road or Beatles, so do not point them at the deployed site.

What was tested

• All 7 tests pass against a local stack (migrate + db:seed, API, Vite), and pass again on a second run (the cleanup works).
• Mutation checks: a low-contrast .muted colour fails all 4 axe tests with color-contrast, and renaming a sort option fails the journey.
• pnpm format:check, pnpm lint, typecheck and pnpm test pass.

How to run

pnpm --filter @t19/e2e exec playwright install chromium   # once
pnpm --filter @t19/server db:seed
pnpm --filter @t19/server dev
pnpm dev
pnpm test:e2e