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/OpcUa/AlarmCommand.cs

@@ -1,5 +1,19 @@
 namespace ZB.MOM.WW.OtOpcUa.Commons.OpcUa;
 
+/// <summary>
+///     Shared DPS topic for inbound alarm commands (<see cref="AlarmCommand"/>). Publishers — the
+///     OPC UA node-manager seam (T18) and the AdminUI path via <c>AdminOperationsActor</c> (T21) —
+///     and the subscriber (<c>ScriptedAlarmHostActor</c>, T19) reference this single constant so a
+///     rename can't silently desynchronise them. Mirrors the
+///     <see cref="Messages.Admin.DriverControlTopic"/> pattern; <c>ScriptedAlarmHostActor</c>
+///     re-exports this as its <c>AlarmCommandsTopic</c> const.
+/// </summary>
+public static class AlarmCommandsTopic
+{
+    /// <summary>The cluster DistributedPubSub topic name inbound alarm commands are published on.</summary>
+    public const string Name = "alarm-commands";
+}
+
 /// <summary>
 ///     Commons-level command carried from an inbound OPC UA Part 9 alarm method call
 ///     (Acknowledge / Confirm / Shelve / AddComment …) back to the scripted-alarm engine. The SDK