scripts/push-docs.js collects docs/**/*.md with public:true frontmatter
and POSTs them (batches of 10, idempotent per slug) to the docs ingest
door after npm publish — release.sh step 12. Absent secret = loud skip
(publish already happened; the serving side can interim-sync); a failed
push exits non-zero so the docs site never silently trails npm. The
combined /docs landing index is deliberately NOT pushed per-repo — it
spans both engine corpora and is authored on the serving side.
