Add support for exposing Duo Agent Platform service port with Kubernetes Service and optional Ingress

Summary

The AI Gateway Helm Chart should support exposing the Duo Agent Platform service port on the ai-gateway pod, creating a Kubernetes Service for it, and optionally creating an Ingress object to route external traffic to the service.

Motivation

This feature will allow customers self-hosting the AI Gateway to enable and use GitLab Duo Agent Platform features. Currently, there is no built-in support in the Helm chart for exposing the Duo Agent Platform service port, which prevents self-hosted deployments from leveraging these capabilities.

Proposal

Add the following capabilities to the Helm chart:

1. Port Exposure: Expose the Duo Agent Platform service port on the ai-gateway pod
2. Kubernetes Service: Create a Kubernetes Service resource that targets the Duo Agent Platform port
3. Optional Ingress: Provide configuration options to optionally create an Ingress object for external routing

Implementation Considerations

• The feature should be configurable via values.yaml
• The Ingress creation should be optional and disabled by default
• Support for common Ingress configurations (host, path, TLS, annotations)
• Ensure compatibility with existing chart configurations
• Consider service type options (ClusterIP, NodePort, LoadBalancer)