gateway-api-migration

Migrates Kustomize modules using NGINX Ingress to Gateway API resources. Dual-target: default Traefik (GatewayClass=traefik), opt-in GKE Gateway (--gateway-class gke-l7-global-external-managed). Handles master/minion topology (common.ingress/ + common.service/) as the primary case, with standalone Ingress as a fallback. Performs cluster-side preflight (CRDs, GatewayClass, policy CRDs, Traefik version probe on…