dependency-review.yml rode mutable refs (@v4 resolves to a BRANCH on
that repo) inside the one workflow whose job is supply-chain hygiene —
now commit-pinned like its siblings, with dependabot keeping the pins
fresh. gate-secret-scan.mjs crashed with an unhandled EPIPE on
oversize diffs (the designed report.oversize branch was unreachable:
the scanner emits no JSON on refusal) — the pipe write now tolerates
early exit and a missing report is an explicit fail-closed exit 1.
Oversize + broken-scanner legs pinned.