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

tests/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/ServiceCollectionExtensionsTests.cs

@@ -193,6 +193,10 @@ public sealed class ServiceCollectionExtensionsTests
         public NodeId LocalNode { get; } = NodeId.Parse("test-node");
         /// <summary>Gets the local roles.</summary>
         public IReadOnlySet<string> LocalRoles { get; } = new HashSet<string>(["driver"]);
+        /// <summary>Gets the local node's cluster-scoped role. None configured in this fake.</summary>
+        public string? ClusterRole => null;
+        /// <summary>Gets the ClusterId extracted from <see cref="ClusterRole"/>. None configured in this fake.</summary>
+        public string? ClusterId => null;
         /// <summary>Determines whether the local node has the specified role.</summary>
         /// <param name="role">The role to check.</param>
         public bool HasRole(string role) => LocalRoles.Contains(role);