feat: add canary ExternalName proxy service

apps/nginx-weighted/canary-proxy-svc.yaml

@@ -0,0 +1,16 @@
+apiVersion: v1
+kind: Service
+metadata:
+  name: nginx-canary-proxy
+  namespace: nginx-mcp
+  labels:
+    app: nginx-canary-proxy
+spec:
+  # ExternalName proxy required because Traefik v3 does not allow
+  # cross-namespace service references inside TraefikService weighted config.
+  # This service bridges nginx-mcp namespace to nginx-canary namespace.
+  type: ExternalName
+  externalName: nginx-canary.nginx-canary.svc.cluster.local
+  ports:
+    - port: 80
+      targetPort: 80