Remove the last shell-owned NAT surface by extracting the iptables logic into a shared Go package and using it from both bangerd and a hidden helper bridge in the CLI.
Route customize.sh and interactive.sh through banger internal nat up/down so the remaining shell helpers reuse the same rule logic, resolve the local banger binary explicitly, and tear NAT back down during cleanup.
Drop nat.sh from the runtime bundle and docs now that NAT is Go-managed everywhere, and keep coverage aligned with the new shared package and helper command.
Validation: go test ./..., bash -n customize.sh interactive.sh verify.sh, make build, and a live ./verify.sh --nat run that installed host rules, reached outbound network access, and cleaned them up successfully.
Fix the Go control plane NAT path now that runtime state lives in the daemon instead of the old repo-local vm.json files.
Add a daemon-native NAT helper that derives uplink, guest IP, and TAP rules directly from VMRecord, applies the existing iptables/sysctl behavior idempotently, and removes the broken nat.sh handoff from vm.go.
Cover uplink parsing and rule generation with unit tests. Validated with go test ./... and make build; a live verify.sh --nat run installed host rules but stopped on the same guest SSH-readiness issue seen in the plain smoke test on this host.
