Check txt-game before a change merges into what the mesh builds (hq ADR 0237)

The repository's layer of the mesh's merge check (mesh/repo-check): the image's install
from the lock file and the server parsed; what cannot run is said.

merge-check.sh

@@ -0,0 +1,18 @@
+#!/bin/sh
+# mesh-check-toolchain: typescript
+#
+# txt-game's own check (novox/hq ADR 0237): the second layer of a pull request's merge check,
+# `mesh/repo-check`, run by the build seat in the mesh's TypeScript toolchain. The gate — the manifest
+# through the controller the mesh runs, every machine composed with it — is the build seat's first layer
+# (`mesh/merge-gate`), run because the mesh's module graph builds txt-game from this branch.
+#
+# What the image's build does, before the merge: the production dependencies installed from the lock file,
+# and the server parsed.
+#
+# **Said, never passed silently**: the server is not started — it listens on a fixed port, which on the
+# build seat's network may be another's — and the game has no tests of its own.
+set -eu
+
+npm ci --omit=dev --no-audit --no-fund --loglevel=error
+node --check server.mjs
+echo "NOT RUN HERE: the server (a fixed port); the game has no tests"