scripts/install-ci-alias.sh installs `ci` (runs the orchestrator as ci-runner
via the prod venv) and `ci-me` (current user). Idempotent, marker-bounded;
supports --system (/etc/profile.d), --uninstall. setup-host-linux.sh gains a
step [7/7] that installs it system-wide, passing CI_PROD_PYTHON/CI_RUN_USER.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
