feat(alarms): AlarmAcknowledgeRequest carries OperatorUser; Galaxy/ScriptedAlarmSource honor it [H6b]

src/Core/ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms/ScriptedAlarmSource.cs

@@ -68,11 +68,11 @@ public sealed class ScriptedAlarmSource : IAlarmSource, IDisposable
         if (acknowledgements is null) throw new ArgumentNullException(nameof(acknowledgements));
         foreach (var a in acknowledgements)
         {
-            // The base interface doesn't carry a user identity — Stream G provides the
-            // authenticated principal at the OPC UA dispatch layer + proxies through
-            // the engine's richer AcknowledgeAsync. Here we default to "opcua-client"
-            // so callers using the raw IAlarmSource still produce an audit entry.
-            await _engine.AcknowledgeAsync(a.ConditionId, "opcua-client", a.Comment, cancellationToken)
+            // Honor the authenticated principal carried on the request when present
+            // (the OPC UA dispatch layer / Stream G threads it through). When absent —
+            // the raw/non-OPC-UA path — default to "opcua-client" so the ack still
+            // produces an audit entry.
+            await _engine.AcknowledgeAsync(a.ConditionId, a.OperatorUser ?? "opcua-client", a.Comment, cancellationToken)
                 .ConfigureAwait(false);
         }
     }