review(ControlPlane): fix premature deploy-seal from unexpected-node ack

Review at HEAD 7286d320. ControlPlane-001 (Medium): ConfigPublishCoordinator.HandleAck
now discards acks from nodes not in _expectedAcks (prevented premature SealDeployment) +
regression test. -002 (flipped-node log count), -003 (redundant mapper arms) tidied.

src/Server/ZB.MOM.WW.OtOpcUa.ControlPlane/Fleet/FleetStatusBroadcaster.cs

@@ -127,16 +127,16 @@ public sealed class FleetStatusBroadcaster : ReceiveActor, IWithTimers
     private void OnTick()
     {
         var stale = DateTime.UtcNow - HeartbeatTimeout;
-        var changed = false;
+        var flippedCount = 0;
         foreach (var kv in _nodes.ToList())
         {
             if (kv.Value.LastSeenUtc < stale && kv.Value.Health == FleetNodeHealth.Healthy)
             {
                 _nodes[kv.Key] = kv.Value with { Health = FleetNodeHealth.Degraded };
-                changed = true;
+                flippedCount++;
             }
         }
-        if (changed) _log.Debug("FleetStatusBroadcaster flipped {Count} nodes to Degraded", changed ? 1 : 0);
+        if (flippedCount > 0) _log.Debug("FleetStatusBroadcaster flipped {Count} nodes to Degraded", flippedCount);
         PublishSnapshot();
     }