[FEATURE]: Propagate role label to pods

Start by locating the operator logic that propagates the existing cluster, node-index, and shard-index labels to pods, then compare it with the ValkeyNode status role shown in the issue. Done means primary and replica pods receive distinct valkey.io/role labels while existing ValkeyCluster resources remain compatible.

Pre-flight checks

• I have searched existing issues and discussions and could not find a duplicate.

Problem / Use case

I'm checking providing access to discover cluster nodes from outside of EKS cluster, but still inside private network. So client connects via LB, discover nodes and connects by IP to required shards.

While this epic is in progress, I'm trying to add Service (LoadBalancer) in front with config like this:

---
apiVersion: v1
kind: Service
metadata:
  name: external-service
spec:
  ports:
    - name: valkey
      port: 6379
      protocol: TCP
      targetPort: 6379
  selector:
    valkey.io/cluster: test-cluster
  type: LoadBalancer

But it adds all pods from the cluster, not only primary. It's not a big issue I would say, but would be useful to be able to limit it.

As I see, this info already exists in ValkeyNode status (see example below), so it should be relatively easy to add it.

Also, it could be useful for other use cases.

NAME               READY   ROLE      POD                         AGE
test-cluster-0-0   true    primary   valkey-test-cluster-0-0-0   40m
test-cluster-0-1   true    replica   valkey-test-cluster-0-1-0   40m

Proposed solution

Operator already propagates Valkey specific labels, like:

  labels:
    valkey.io/cluster: test-cluster
    valkey.io/node-index: "0"
    valkey.io/shard-index: "0"

I think one more could be added, like valkey.io/role: primary (or replica)

Scope of change

Small (small CRD field or controller behaviour tweak)

API / behaviour impact

• This change is backwards-compatible with existing ValkeyCluster CRs.
• This change introduces a breaking API change in v1alpha1.

Contribution

• I would like to implement this feature myself.
• I would like to help review or test this feature.

Additional context

No response