Adds a host-agnostic elway play + fleet driver that stand up an
`infra-ops` system user (dedicated ed25519 key, NOPASSWD sudo with
log_output audit, docker group) so the infra-ops agent completes
DevOps work end-to-end instead of handing sudo steps back to the
operator. Scoped to PFI-owned Linux boxes; tiered (compute/app/
sensitive-infra) with SureFire/corviduo/esh/Synology explicitly
excluded. Validated live on irv-ml1.
