[Infra] Stand up a full CI pipeline (lint, typecheck, unit, e2e, build, a11y)

[grantfox-oss]

Telegram (ask questions / claim the issue here first): https://t.me/+DOylgFv1jyJlNzM0

Why this matters

There is no .github/workflows directory in this repo, so nothing is verified on push or pull request. Prettier, ESLint, TypeScript, Jest unit tests, Playwright e2e, the production build, and the a11y audit can all break on main with no signal. Every other quality issue in this batch depends on a gate that actually runs.

Acceptance criteria

• Add .github/workflows/ci.yml running on pull_request and push to main
• Jobs: install (npm ci with cache), prettier check, eslint, typecheck (tsc --noEmit), jest unit with coverage, next build, and a Playwright e2e job with the report uploaded as an artifact
• Run the existing audit:a11y (axe-playwright) as its own job or step
• Node 20, fail fast off so all jobs report, and concurrency cancel-in-progress for the same ref
• CI is green on a clean checkout of main (fix or file follow-ups for anything it surfaces)

Files to touch

• .github/workflows/ci.yml (new)
• package.json (scripts referenced by CI, see the scripts issue)
• playwright.config.ts, e2e/
• jest.config.js

Implementation notes

Pair this with the test and typecheck script issue so CI has real commands to call. Cache ~/.npm and the Playwright browser download.

Out of scope

• Deployment / release workflows
• Required-status-check branch protection (maintainer setting)

[davidmaronio]

I have read through the issue and the related code, and I am comfortable picking this up. I will keep the change small and focused on what the issue describes, add a test where it makes sense, and open a PR. I can have it ready within 2 days.

[grantfox-oss]

🦊 GrantFox — @davidmaronio has been assigned to this issue as part of the Official Campaign campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #2)
2. Your PR will be reviewed by the LabsCrypt maintainers

Good luck! Track your progress on GrantFox.