build: the gate is scripts/check.sh, and CI goes

The Gitea Actions gate repeated, after the merge, what a release already runs
before it, and its runner shared the git host's container: one run there
starved Gitea of memory until it stopped answering. The lanes now live in
scripts/check.sh, run the same by the release dispatcher and by hand, and the
gate-contract test holds its lines (the ruff and pip-audit checks read it
instead of the workflow). The two audits only CI ran join the gate: pip-audit
over the lock (pinned in the test image, blocking at any severity) and npm
audit of the production dependencies. The engine contracts drop the CI
containers; the register records that pushes have no server-side gate.

Dockerfile

@@ -11,7 +11,7 @@ ARG BUILD_DATE=
 
 # Stage 1: build the frontend SPA
 # The major is pinned to `.nvmrc` and held there by frontend/src/lib/nodeEngine.contract.test.ts:
-# this image, the CI gate's image and the dev machine must be ONE engine (see that test for why).
+# this image and the dev machine the gate runs on must be ONE engine (see that test for why).
 FROM node:24-alpine AS frontend
 WORKDIR /fe
 # Deps first, keyed on the lockfile, so editing app source never re-resolves node_modules.
@@ -79,8 +79,8 @@ RUN printf 'Types: deb\nURIs: http://deb.debian.org/debian\nSuites: bookworm\nCo
     && rm -rf /var/lib/apt/lists/*
 
 # Install from the PINNED lock (requirements.lock, generated from requirements.txt) so the image is
-# byte-reproducible and the exact versions are the ones pip-audit scanned in CI — not whatever floats
-# up from the floor ranges on build day. Regenerate the lock when requirements.txt changes (see its header).
+# byte-reproducible and the exact versions are the ones the gate's pip-audit scanned — not whatever
+# floats up from the floor ranges on build day. Regenerate the lock when requirements.txt changes (see its header).
 # pip itself is removed once it has installed the lock (E32): nothing runs it at runtime, and it carries
 # its own VENDORED copies of urllib3, msgpack and setuptools, which Trivy reports as the image's own —
 # an attack surface and a CVE stream for a tool the running app never calls.