Adds `act-swarm-zombie app=<id>` which runs the swarm matrix-app test and leaves
the DinD cluster + lab network alive afterwards (INFINITO_KEEP_SWARM_NODES=true
forwarded via the new ACT_ENV passthrough in workflow.sh) so failures can be
post-mortem inspected with `make act-swarm-exec node=… cmd=…`,
`make act-swarm-shell node=…`, and finally released with `make act-swarm-down`.
Consolidates the swarm-test topology (manager / worker / nfs-server names, lab
network, NFS export base) into scripts/tests/deploy/swarm/topology.sh as the
single source of truth: 13_cleanup.sh and shell_node.sh source it directly,
the GitHub Actions workflow ingests it into $GITHUB_ENV via a setup step,
replacing the duplicate env: block entries.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>