feat: migrate purelb to ArgoCD

Migrate PureLB load balancer from Terragrunt to ArgoCD/Kustomize.
Deploys purelb v0.13.0 with two LBNodeAgent and two ServiceGroup CRs
(common: 198.18.200.0/24, dmz: 198.18.199.0/24).
Adds LBNodeAgent and ServiceGroup to kubeconform skip list (no CRD catalog schema).

💘 Generated with Crush

Assisted-by: Claude Sonnet 4.6 via Crush <crush@charm.land>

argocd/applicationsets/platform.yaml

@@ -21,6 +21,7 @@ spec:
       - path: apps/overlays/*/jfrog
       - path: apps/overlays/*/node-feature-discovery
       - path: apps/overlays/*/puppet
+      - path: apps/overlays/*/purelb
       - path: apps/overlays/*/reflector-system
       - path: apps/overlays/*/reloader-system
       - path: apps/overlays/*/reposync