Host-mode jobs execute directly on the bare runner container rather
than a per-job container, and actions/checkout is a JS action — it
needs `node` on PATH to run at all, which the runner image doesn't
ship. Failed every run with "Cannot find: node in PATH" before any
other step got a chance to install anything.
On every push/PR: run Domain.Tests, then docker compose build to validate
the full stack still builds. On push to master: also docker compose up -d
to redeploy. COMPOSE_PROJECT_NAME is pinned to ruvdstests so a run from a
runner-managed checkout always targets the existing stack/volumes instead
of spinning up a duplicate under a different project name.
