feat: migrate elastic-system to ArgoCD

Migrate ECK operator from Terragrunt to ArgoCD/Kustomize.
Deploys eck-operator v3.2.0 with 2 replicas and PodDisruptionBudget
in the elastic-system namespace.

💘 Generated with Crush

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

argocd/projects/platform.yaml

@@ -8,14 +8,15 @@ spec:
   description: Platform infrastructure and core services
   sourceRepos:
     - https://git.unkin.net/unkin/argocd-apps
+    - https://charts.jetstack.io
+    - https://cloudnative-pg.github.io/charts
+    - https://helm.elastic.co
+    - https://intel.github.io/helm-charts/
+    - https://kubernetes-sigs.github.io/external-dns/
+    - https://releases.rancher.com/server-charts/stable
+    - oci://gcr.io/k8s-staging-nfd/charts
     - oci://ghcr.io/emberstack/helm-charts
     - oci://ghcr.io/woodpecker-ci/helm/woodpecker
-    - https://releases.rancher.com/server-charts/stable
-    - https://charts.jetstack.io
-    - https://kubernetes-sigs.github.io/external-dns/
-    - https://cloudnative-pg.github.io/charts
-    - oci://gcr.io/k8s-staging-nfd/charts
-    - https://intel.github.io/helm-charts/
   destinations:
     - namespace: '*-system'
       server: https://kubernetes.default.svc