feat: migrate purelb to ArgoCD (#84)

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>

Reviewed-on: #84

apps/base/purelb/kustomization.yaml

@@ -0,0 +1,8 @@
+---
+apiVersion: kustomize.config.k8s.io/v1beta1
+kind: Kustomization
+
+resources:
+  - namespace.yaml
+  - lbnodeagents.yaml
+  - servicegroups.yaml