feat(alerts): AdminUI alarm ack/shelve via AdminOperationsActor singleton

T21: add an AdminUI path for acknowledging/shelving alarms that routes
through the admin-pinned AdminOperationsActor cluster singleton, which
republishes onto the same 'alarm-commands' DPS topic the OPC UA method
path (T18) and the engine subscriber (T19) use. The broadcast + the
ScriptedAlarmHostActor ownership filter handle cross-node routing, so
the singleton needs no knowledge of which node owns the alarm.

- Commons: AcknowledgeAlarmCommand/ShelveAlarmCommand (+ result records)
  and a shared AlarmCommandsTopic const; ScriptedAlarmHostActor now
  re-exports that const (mirrors the DriverControlTopic pattern).
- AdminOperationsActor: two handlers map the control-plane messages to
  AlarmCommand (Acknowledge / OneShotShelve / TimedShelve / Unshelve,
  threading User/Comment/UnshelveAtUtc) and publish via the DPS mediator.
- IAdminOperationsClient + AdminOperationsClient: typed Acknowledge/Shelve
  ask wrappers mirroring StartDeploymentAsync.
- Alerts.razor: per-row DriverOperator-gated Ack/Shelve/Unshelve controls;
  operator name from AuthenticationState. Timed-shelve datetime UI deferred.
- 5 TestKit tests (mediator-probe subscribed to alarm-commands) verifying
  each kind's mapping + reply; 56/56 ControlPlane tests green.

src/Core/ZB.MOM.WW.OtOpcUa.Commons/Messages/Admin/AcknowledgeAlarmCommand.cs

@@ -0,0 +1,28 @@
+namespace ZB.MOM.WW.OtOpcUa.Commons.Messages.Admin;
+
+/// <summary>
+///     AdminUI → AdminOperationsActor: acknowledge one alarm on behalf of an operator. The admin
+///     singleton maps this to a <c>Commons.OpcUa.AlarmCommand</c> with <c>Operation = "Acknowledge"</c>
+///     and republishes it onto the cluster <c>alarm-commands</c> topic, where the owning
+///     <c>ScriptedAlarmHostActor</c> filters by ownership and drives the engine. Routing this through
+///     the admin-pinned singleton lets the AdminUI act without knowing which node owns the alarm —
+///     the broadcast + ownership filter handle cross-node delivery.
+/// </summary>
+/// <param name="AlarmId">The alarm's ScriptedAlarmId (the <c>AlarmTransitionEvent.AlarmId</c> shown on the row).</param>
+/// <param name="User">The authenticated operator who triggered the acknowledgement.</param>
+/// <param name="Comment">Optional free-text comment supplied with the acknowledgement; null when none.</param>
+/// <param name="CorrelationId">Round-trip correlation token.</param>
+public sealed record AcknowledgeAlarmCommand(
+    string AlarmId,
+    string User,
+    string? Comment,
+    Guid CorrelationId);
+
+/// <summary>Reply for <see cref="AcknowledgeAlarmCommand"/>.</summary>
+/// <param name="Ok">True iff the command was published without error.</param>
+/// <param name="Message">Failure reason; null on success.</param>
+/// <param name="CorrelationId">Echoes the request's correlation token.</param>
+public sealed record AcknowledgeAlarmResult(
+    bool Ok,
+    string? Message,
+    Guid CorrelationId);