FEAT(k8s): add k8s monitoring dashboard

- Add monitoring page with Grafana-style UI and real-time charts
- Implement Prometheus metrics API endpoint with comprehensive queries
- Add Chart.js for visualizing cluster metrics
- Include Overview, Resources, Kubernetes, and Network sections
- Support both production (Prometheus) and development (mock) data
- Add PROMETHEUS_URL environment variable to deployment

deploy/k8s/base/deployment.yaml

@@ -43,6 +43,8 @@ spec:
                   name: argocd-ca-cert
                   key: ca.crt
                   optional: true
+            - name: PROMETHEUS_URL
+              value: "http://prometheus.monitoring.svc.cluster.local:9090"
           resources:
             requests:
               memory: "100Mi"