mara, on #4128: add a CI step (separate from the existing one) that
only flags error-level vale hits, so it can be made a required check
without also gating merges on the pre-existing warning/suggestion
backlog. The full job stays as-is, advisory, for that backlog.
Also brought docs/scheduler/ci.md's CI-checks table back in sync with
reality (it was missing the doc-pointer lint job already; now lists
both vale jobs and their required-check status).
c13499c839