Add support for configurable NodePort router service and safe local overrides in Helm chart

[alikhabazian]

Describe the feature

When trying to customize the routerSpec to use a NodePort service and set a fixed nodePort, I ran into several issues:

1. The chart does not support defining a nodePort value in values.yaml.
   As a result, every helm upgrade recreates the router service and assigns
   a new (random) NodePort—even when no configuration has changed.

2. Setting routerSpec.serviceType to NodePort forces Kubernetes to replace
   the existing service with a new one of type ClusterIP during upgrades.

Why do you need this feature?

I resolved these issues locally by extending the Helm chart to support a
routerSpec.nodePorts field and adding safe conditional checks in the service
template. This allows the router service to:

• Keep a stable NodePort across upgrades
• Avoid being replaced or recreated unnecessarily
• Allow users to define custom NodePort values cleanly from values.yaml

I would like to submit a pull request adding this improved NodePort support to
the upstream chart.

Additional context

No response

[officer47p]

This would help us a lot and prevent people from manually doing it.