feat(mesh): ClusterRoleInfo exposes the node's own cluster-scoped role

Phase 6 Task 1. IClusterRoleInfo gains ClusterRole/ClusterId, derived from
the node's configured AkkaClusterOptions.Roles at construction time (not
live Cluster.State) so the identity is available before the cluster forms.
First cluster-scoped role wins when more than one is configured, logged as
a Warning. Updates the FakeClusterRoleInfo test double in
ServiceCollectionExtensionsTests to satisfy the new interface members.

Claude-Session: https://claude.ai/code/session_01GASWkNEi68FSCtvr6rLoEW

src/Core/ZB.MOM.WW.OtOpcUa.Commons/Interfaces/IClusterRoleInfo.cs

@@ -14,6 +14,21 @@ public interface IClusterRoleInfo
     NodeId LocalNode { get; }
     /// <summary>Gets the set of roles assigned to the local node.</summary>
     IReadOnlySet<string> LocalRoles { get; }
+
+    /// <summary>
+    /// Gets the local node's cluster-scoped role (e.g. <c>cluster-SITE-A</c>), or <c>null</c> when
+    /// the node carries none. Derived from the node's OWN configured roles at construction time —
+    /// NOT from live cluster membership — so it is available before the cluster forms (per-cluster
+    /// mesh, Phase 6). When more than one cluster-scoped role is configured, the first one wins.
+    /// </summary>
+    string? ClusterRole { get; }
+
+    /// <summary>
+    /// Gets the ClusterId extracted from <see cref="ClusterRole"/> (e.g. <c>SITE-A</c>), or
+    /// <c>null</c> when the node carries no cluster-scoped role.
+    /// </summary>
+    string? ClusterId { get; }
+
     /// <summary>Checks if the local node has the specified role.</summary>
     /// <param name="role">Role name to check.</param>
     /// <returns>True if the local node has the role; otherwise, false.</returns>