refactor: remove ClusterClient streaming path (DebugStreamEvent), events flow via gRPC

src/ScadaLink.Commons/Messages/DebugView/DebugStreamEvent.cs

@@ -1,8 +0,0 @@
-namespace ScadaLink.Commons.Messages.DebugView;
-
-/// <summary>
-/// Wraps a debug stream event (AttributeValueChanged or AlarmStateChanged) with
-/// the correlationId for routing back to the correct DebugStreamBridgeActor on central.
-/// Sent from InstanceActor → SiteCommunicationActor → ClusterClient → CentralCommunicationActor.
-/// </summary>
-public record DebugStreamEvent(string CorrelationId, object Event);