ci: verify pull requests

[kriss39]

Which Linear task is linked to this PR?

None.

Why was it implemented this way?

The repository currently validates pull-request titles but does not run the existing typecheck, build, or lint commands for pull requests. A malformed declaration change can therefore merge without automated validation and only fail later during release.

This workflow reuses the existing pnpm-install composite action and runs the project's existing verification commands. It has no publish, release, deployment, or secret-bearing steps.

Visual showcase (Screenshots or Videos)

Not applicable.

Checklist before requesting a review

• I have performed a self-review and testing of my code.
• This pull request is focused and addresses a single problem.
• If this PR modifies the Types API or adds new features that require documentation, I have updated the documentation in the public-docs repository.

Verification

• prettier --check .github/workflows/verify.yaml
• tsc --project tests/tsconfig.json
• CJS build using the package build compiler arguments