feat: initial GitOps infrastructure

ArgoCD app definitions, Kustomize manifests for health-app,
cert-manager ClusterIssuer, and AppProject configuration.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

environments/health-app/base/kustomization.yaml

@@ -0,0 +1,13 @@
+apiVersion: kustomize.config.k8s.io/v1beta1
+kind: Kustomization
+
+namespace: health-app
+
+resources:
+  - deployment.yaml
+  - service.yaml
+  - ingress.yaml
+  - networkpolicy.yaml
+
+commonLabels:
+  app.kubernetes.io/managed-by: argocd