Add ServiceMonitors and Grafana dashboards for Harbor, External-DNS, and Ingress-NGINX

- Created ServiceMonitor for Harbor (harbor-core, harbor-exporter, harbor-jobservice, harbor-registry)
  - Port: http-metrics (8001)
  - Scrape interval: 30s
  - Verified metrics: harbor_core_http_request_duration_seconds_count

- Created ServiceMonitor for External-DNS
  - Port: http (7979)
  - Scrape interval: 30s
  - Verified metrics: external_dns_registry_endpoints_total

- Created ServiceMonitor for Ingress-NGINX
  - Port: metrics (10254)
  - Scrape interval: 30s
  - Verified metrics: nginx_ingress_controller_requests

- Added Grafana dashboards:
  - Harbor Overview (dashboard 16366)
  - External-DNS (dashboard 15038)
  - Ingress-NGINX Controller (dashboard 9614)

All ServiceMonitors deployed and actively scraping. Prometheus targets confirmed UP.

cluster/platform/ingress-nginx/servicemonitor.yaml

@@ -0,0 +1,37 @@
+# ------------------------------------------------------------------------------
+# Ingress-NGINX Controller Metrics - ServiceMonitor
+#
+# Configures Prometheus Operator to scrape Ingress-NGINX Controller metrics
+# 
+# Scrape interval: 30s
+# Endpoint: /metrics on port 10254
+# Metrics namespace: nginx_ingress_* (nginx_ingress_controller_requests, etc.)
+# ------------------------------------------------------------------------------
+apiVersion: monitoring.coreos.com/v1
+kind: ServiceMonitor
+metadata:
+  name: ingress-nginx-metrics
+  namespace: ingress-nginx
+  labels:
+    app.kubernetes.io/name: ingress-nginx
+    app.kubernetes.io/component: metrics
+    # Label selector for kube-prometheus-stack discovery
+    release: monitoring
+spec:
+  # Select the ingress-nginx-controller-metrics service
+  selector:
+    matchLabels:
+      app.kubernetes.io/name: ingress-nginx
+      app.kubernetes.io/component: controller
+  
+  # Namespace selector
+  namespaceSelector:
+    matchNames:
+    - ingress-nginx
+  
+  # Scrape endpoint configuration
+  endpoints:
+  - port: metrics
+    interval: 30s
+    scrapeTimeout: 10s
+    path: /metrics