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/projects/platform.yaml

@@ -12,7 +12,7 @@ spec:
     - https://cloudnative-pg.github.io/charts
     - https://helm.elastic.co
     - https://helm.releases.hashicorp.com
-    - https://gitlab.com/api/v4/projects/20400619/packages/helm/stable
+    - https://purelb.github.io/purelb/charts
     - https://intel.github.io/helm-charts/
     - https://kubernetes-sigs.github.io/external-dns/
     - https://releases.rancher.com/server-charts/stable