ci-pnpm never runs the lint script

[george-elphick-talieisin]

Problem

ci-pnpm.yml detects and runs typecheck, build and test scripts, but never lint. A repo whose lint lives only in a lint script therefore gets no lint in CI:

• caersid has "lint": "eslint . --concurrency ${ESLINT_CONCURRENCY:-4}", and CI never runs it. Its main branch has built up ~75 lint errors as a result (count reported by the caersid session).
• estimist isn't affected: its test script runs pnpm run lint && pnpm run format:check && vitest run.

Proposal

Add a has_lint detection alongside the existing ones in the "Detect scripts" step, and a blocking Lint step that runs pnpm run lint when the script exists.

• Blocking, not advisory. ci-uv.yml runs uv run ruff check . || true, which never fails anything; that is the pattern to avoid.
• Order: before Build, next to Typecheck, so it fails fast and doesn't wait on next build.

Things to decide

1. Rollout. Detection turns lint on for every caller with a lint script the moment they bump their pin. caersid would go red immediately. Options:
   • fix caersid's lint errors first, then land this; or
   • ship it behind an opt-in input (e.g. lint: true, default false) and flip the default once callers are clean.
2. Double runs. estimist would run lint twice: once in the new step, once inside test. Either accept it (oxlint is fast), or estimist drops lint from test once the shared step exists.
3. Format check. Same gap for format:check. It could ride along, or stay a separate decision.

Out of scope

Fixing caersid's existing lint errors. That's caersid work, sequenced per option 1.