ci: type-check evals in pull request workflow

[ANIRUDDHA ADAK (aniruddhaadak80)]

Summary

Add the existing eval TypeScript project to the Ubuntu leg of the non-Windows workflow.

Why

The root TypeScript configuration excludes evals, while the existing test and build commands do not type-check that project. Eval type errors could therefore pass CI without running model-backed evals.

Changes

• Run npm run typecheck:evals only on Linux.
• Leave eval execution out of CI; it requires Copilot/network access and can incur cost.
• The duplicate-run portion of CI: type-check evals in CI, and stop double-running the matrix on every PR #6 is already stale: push is currently limited to main, so this PR does not change triggers or add concurrency.

Testing

• npm run typecheck:evals (new CI step; not executed yet)
• npm test (existing CI command; not executed yet)
• npm run build (existing CI command; not executed yet)

Local execution was not performed because this contribution is remote-only; no local checkout or source was used.

CI status

• The first Non-Windows and Windows Actions runs are action_required with no jobs or logs; upstream workflow approval is required before the commands can run.
• license/cla passed.
• No npm result is claimed until an Actions run executes.

Fixes #6