feat(opcua): emit Bad blip + AuditWriteUpdateEvent + sync fail-fast on failed device write

src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/OtOpcUaNodeManager.cs

@@ -1064,6 +1064,8 @@ public sealed class OtOpcUaNodeManager : CustomNodeManager2
     ///     </list>
     ///     Silent value-wise — this node manager carries no logger; the gateway logs the underlying write failure
     ///     and the SDK trace captures any audit-report failure.
+    ///     <para><c>internal</c> (not private) so the behavioural test drives the blip-then-settle continuation
+    ///     against a booted node manager — see <c>NodeManagerWriteRevertTests</c>.</para>
     /// </summary>
     /// <param name="nodeId">The string id of the written variable node.</param>
     /// <param name="outcome">The device-write outcome routed back by the gateway.</param>
@@ -1072,7 +1074,7 @@ public sealed class OtOpcUaNodeManager : CustomNodeManager2
     /// <param name="priorStatus">The node's real status captured before the optimistic write.</param>
     /// <param name="clientUserId">The writing principal's user-id string (the identity's DisplayName), threaded
     /// from <see cref="OnEquipmentTagWrite"/> to populate the audit event's ClientUserId; null when unknown.</param>
-    private void RevertOptimisticWriteIfNeeded(
+    internal void RevertOptimisticWriteIfNeeded(
         string nodeId, NodeWriteOutcome outcome, object? optimisticValue, object? priorValue, StatusCode priorStatus,
         string? clientUserId)
     {
@@ -1132,7 +1134,10 @@ public sealed class OtOpcUaNodeManager : CustomNodeManager2
     /// <param name="priorValue">The node's real pre-write value (the audit OldValue).</param>
     /// <param name="clientUserId">The writing principal's user-id string; null when unknown.</param>
     /// <returns>A populated, unreported <see cref="AuditWriteUpdateEventState"/>.</returns>
-    private AuditWriteUpdateEventState BuildWriteFailureAuditEvent(
+    /// <remarks><c>internal</c> (not private) so <c>NodeManagerWriteRevertTests</c> can assert the populated
+    /// audit fields at the nearest deterministic seam (the end-to-end <c>Server.ReportEvent</c> dispatch would
+    /// need a subscribed event monitored-item to observe).</remarks>
+    internal AuditWriteUpdateEventState BuildWriteFailureAuditEvent(
         BaseDataVariableState variable, NodeWriteOutcome outcome, object? optimisticValue, object? priorValue,
         string? clientUserId)
     {