Add a configurable managed-by annotation (key and value) to all Kubernetes resources created by our controllers

[rambohe-ch]

Description

All Kubernetes resources created by our controllers (e.g. InferenceSet, InferencePool, EPP Deployment/Service, HTTPRoute, ScaledObject, etc.) should carry a managed-by annotation that identifies the owner/originator of the resource. Both the annotation key and value must be configurable via the Helm chart to provide sufficient flexibility.

Motivation / Use cases

1. Auditing — the platform needs to audit all managed resources in a Kubernetes cluster. A consistent managed-by annotation makes it possible to enumerate and track every resource we provision.
2. BYO (bring-your-own) clusters — in a customer-owned cluster, our managed resources coexist with the customer's own resources. The annotation is needed to reliably distinguish platform-managed resources from customer (cx) resources.

Requirements

• Stamp a managed-by annotation on every Kubernetes resource that our controllers create.
• Both the annotation key and value must be configurable via the Helm chart (neither is hard-coded), so callers can set an arbitrary key/value (e.g. the owning project/tenant).
• When no value is provided, the annotation should be omitted (or fall back to a sensible default — to be decided).

Acceptance criteria

• The Helm chart exposes configurable values for both the annotation key and value.
• The configured key/value is propagated to the annotation on all resources created by our controllers.
• Existing releases that don't set the field continue to work (backward compatible).