ci: add lint and typecheck workflow on push/PR

[hellozzm]

Summary

Add CI workflow that runs biome check and tsc on push and PR.

Fixes #147

[anton-pascal]

Drive-by note: @Aymericr shipped #369 about an hour ago which added the lint+typecheck workflow and closed #147. Thanks for putting this together back in March — sorry it sat. Feel free to close if you'd like; happy to do it for you otherwise.

[Aymericr]

Thanks for this! A CI quality gate has since landed on main — .github/workflows/ci.yml runs bun run check (lint + format) and bun run check-types on every push/PR, which is exactly what this proposes. So this is already covered. Closing as resolved (this also overlaps #208). Appreciate the contribution!