Function build_secrets_writer_role 

pub fn build_secrets_writer_role(namespace: &str) -> Role

Build the namespaced Role granting the operator the mutating verbs on Secrets.

B-5 hardening: cluster-wide Secret access in the operator ClusterRole is read-only; create/update/patch/delete are confined to this namespaced Role, bound only in the operator namespace. This prevents a compromised operator from creating, modifying, or deleting Secrets in other namespaces.