chore: add ui test runner, run tests in CI, fix stale agent docs

[tmccoy14]

Tooling and docs housekeeping, split out of feat/select-search so that PR can stay focused on the feature. Nothing here changes the published library, so there's no changelog entry or version bump.

Tests

• Adds Vitest, jsdom and Testing Library as dev dependencies of @eqtylab/equality, with config in packages/ui/vitest.config.ts and tests under packages/ui/tests/. Tests live outside src, so they're never bundled or published (files is dist only).
• Adds a root pnpm test (pnpm -r run test) and a Test step in the Code Quality workflow. The docs package's 103 existing tests have never run in CI; now they do.
• The ui script is vitest run --passWithNoTests for now, because the first suite lands with feat/select-search. That PR drops the flag.

Agent docs

• AGENTS.md (CLAUDE.md links to it):
  • the docs path is now packages/demo/src/content/docs/components (it was missing docs/);
  • the llms.txt and .md routes now point at packages/docs/src/runtime/routes (the old path no longer exists);
  • the unfinished "Tokens are automatically built by the" sentence is completed;
  • pnpm build and pnpm dev are described correctly.
• create-component skill: same docs path fix.
• equality-design-system skill: adds the name translation table that AGENTS.md tells contributors to update. Until now the table didn't exist. It starts with ten mappings (modal → Dialog, drawer → Sheet, chip → Badge and so on), each checked against an actual export. Also fixes a stray backtick on DateRangePicker.

Config

• Removes baseUrl from the demo tsconfig (deprecated in TypeScript 6) and makes the paths entries relative. The demo type errors are the same before and after (17 existing ones in astro.config.mjs), and the Astro build resolves every alias.

Verification

pnpm lint, pnpm format:check, pnpm build and pnpm test all pass locally on Node 24. The docs tests use Node's built-in TypeScript support, which needs Node 22.18 or later; CI's node-version: 22 should resolve to a new enough release, but it's worth confirming on this PR's run.

🤖 Generated with Claude Code

[matthewmr-eqty]

Thanks Tucker. Nice to have the tests running in CI now.