Three idempotent stages with guards (probe-before-mutate), rrun() for all
remote mutations, rprobe() for unconditional state queries. Reads
hardware.swap.mb from node.yaml (default 2048 MB). Adds swap.mb: 2048
to hosts/lustro/node.yaml so the value is declarative.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
