feat: migrate elastic-system to ArgoCD (#79)

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>

Reviewed-on: #79

apps/base/elastic-system/kustomization.yaml

@@ -0,0 +1,6 @@
+---
+apiVersion: kustomize.config.k8s.io/v1beta1
+kind: Kustomization
+
+resources:
+  - namespace.yaml

apps/base/elastic-system/namespace.yaml

@@ -0,0 +1,7 @@
+---
+apiVersion: v1
+kind: Namespace
+metadata:
+  labels:
+    app.kubernetes.io/name: elastic-system
+  name: elastic-system

apps/overlays/au-syd1/elastic-system/kustomization.yaml

@@ -0,0 +1,16 @@
+---
+apiVersion: kustomize.config.k8s.io/v1beta1
+kind: Kustomization
+
+namespace: elastic-system
+
+resources:
+  - ../../../base/elastic-system
+
+helmCharts:
+  - name: eck-operator
+    repo: https://helm.elastic.co
+    version: "3.2.0"
+    releaseName: elastic-operator
+    namespace: elastic-system
+    valuesFile: values.yaml

apps/overlays/au-syd1/elastic-system/values.yaml

@@ -0,0 +1,11 @@
+replicaCount: 2
+resources:
+  limits:
+    cpu: 1
+    memory: 1Gi
+  requests:
+    cpu: 10m
+    memory: 150Mi
+podDisruptionBudget:
+  enabled: true
+  minAvailable: 1

argocd/applicationsets/platform.yaml

@@ -15,6 +15,7 @@ spec:
       - path: apps/overlays/*/cert-manager
       - path: apps/overlays/*/certificates
       - path: apps/overlays/*/cnpg-system
+      - path: apps/overlays/*/elastic-system
       - path: apps/overlays/*/externaldns
       - path: apps/overlays/*/inteldeviceplugins-system
       - path: apps/overlays/*/jfrog

argocd/projects/platform.yaml

@@ -10,6 +10,7 @@ spec:
     - 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