feat: add tile matcher + games layer

[ShaunSHamilton]

Summary

What changes? Why?

Details

Component - TileMatcher

• pairs model: one face → duplicated (classic concentration), two faces → related match (term↔definition). Deck size = 2 × pairs.length.
• Faces accept any node (text, , , icon) or { content, label } for accessible names on image tiles.
• animateFlip (3D flip vs instant), faceDown, columns, mismatchDelay, disabled, shuffle/seed (seeded mulberry32 PRNG for determinism).
• Callbacks: onMatch, onMismatch, onComplete({ moves, matches }).
• A11y: native tiles, per-tile aria-label, aria-live status region, matched tiles disabled, reduced-motion aware.

Styling - .tile-matcher* BEM appended to components.css using existing tokens; 3D rotateY flip mirroring the Modal transform pattern; handles flip / no-flip / faces-open modes.

Layer wiring - new src/games/ barrel, added to index.ts, tsup.config.ts, ./games export in package.json, and LAYER_SUBPATHS in package.test.ts. Build emits dist/games.{js,cjs,d.ts,d.cts}.

Docs - category:'game' enum, tile-matcher.mdx, showcase + demo island.

Changeset - .changeset/tile-matcher-game.md on uikit + uikit-css.

Type of change

• feat — new behavior
• fix — bug fix
• refactor — no behavior change
• docs — documentation only
• chore / ci / build — tooling, infra
• test — tests only

Pre-flight checklist

• pnpm changeset added (skip for chore / docs / test / ci-only PRs)
• pnpm test, pnpm typecheck, pnpm lint, pnpm format:check clean locally
• Visual goldens refreshed if UI changed (pnpm test:visual:update on macOS;
  Linux goldens regenerated via the Playwright Docker image — see
  docs/runbooks/deploy-docs.md)
• apps/docs/public/{_headers,_redirects,robots.txt} unchanged or
  rebaselined deliberately
• ADR added or updated if a locked decision changes (see
  docs/adr/README.md)

Screenshots / GIF

[ShaunSHamilton]

@moT01 Seeing as we are moving fast and breaking things, I added this. If you do not have a completely different idea, then feel free to merge.