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/service.yaml

@@ -0,0 +1,15 @@
+apiVersion: v1
+kind: Service
+metadata:
+  name: health-app
+  labels:
+    app.kubernetes.io/name: health-app
+spec:
+  type: ClusterIP
+  selector:
+    app.kubernetes.io/name: health-app
+  ports:
+    - name: http
+      port: 80
+      targetPort: http
+      protocol: TCP