feat(chart): add configurable Service externalTrafficPolicy

[Copilot]

This change adds Helm chart support for configuring Kubernetes Service.spec.externalTrafficPolicy, enabling deployments behind ingress/LB to preserve client source IPs for IP filtering and gateway logs.

• Service configuration

  • Added service.externalTrafficPolicy to chart values as an optional setting (Cluster or Local).

• Template behavior

  • Updated templates/service.yaml to render spec.externalTrafficPolicy only when:
    • service.externalTrafficPolicy is set, and
    • service.type is NodePort or LoadBalancer.

• Chart documentation

  • Regenerated chart README so the new value is included in the Networking configuration table.

service:
  type: LoadBalancer
  externalTrafficPolicy: Local