fix(adminui): wire Test Connect probes + live panels on admin-only nodes

Both bugs surfaced only on split-role deployments (the MAIN cluster's
admin-only nodes), where the AdminUI runs without the driver role.

- Test Connect returned "No probe registered" for every driver: the
  IDriverProbe set was registered only under the driver role, but the
  admin-operations singleton that consumes it is pinned to admin. Extract
  AddOtOpcUaDriverProbes() (idempotent via TryAddEnumerable) and call it
  in the hasAdmin path too.

- Live driver-status/alerts/script-log panels showed "SignalR error:
  Connection refused": these Blazor Server components opened a HubConnection
  to their own hub via the browser's public URL, which server-side code
  can't reach behind Traefik (host :9200 -> container :9000). Read the
  in-process source directly instead -- DriverStatus via
  IDriverStatusSnapshotStore.SnapshotChanged, Alerts/ScriptLog via a new
  IInProcessBroadcaster<T>. Fleet status was unaffected (reads DB/ActorSystem).

Adds unit tests for probe registration, the snapshot-store event, and the
broadcaster.

src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Hubs/IDriverStatusSnapshotStore.cs

@@ -6,10 +6,21 @@ namespace ZB.MOM.WW.OtOpcUa.AdminUI.Hubs;
 ///     Singleton last-snapshot-per-instance cache. Populated by
 ///     <c>DriverStatusSignalRBridge</c> as it forwards DPS messages; read by
 ///     <see cref="DriverStatusHub.JoinDriver"/> so newly-joined clients see current state
-///     without waiting for the next change event.
+///     without waiting for the next change event, and subscribed to directly by the Blazor
+///     Server <c>DriverStatusPanel</c> via <see cref="SnapshotChanged"/>.
 /// </summary>
 public interface IDriverStatusSnapshotStore
 {
     void Upsert(DriverHealthChanged snapshot);
     bool TryGet(string driverInstanceId, out DriverHealthChanged snapshot);
+
+    /// <summary>
+    ///     Raised after every <see cref="Upsert"/> with the just-stored snapshot. Lets in-process
+    ///     consumers (the Blazor Server <c>DriverStatusPanel</c>) receive live updates by reading
+    ///     this singleton directly instead of opening a self-targeted SignalR connection — which a
+    ///     server-side Blazor component cannot reach when the public URL (e.g. a reverse-proxy port)
+    ///     differs from the local Kestrel bind. Handlers run on the caller's thread (the bridge
+    ///     actor), so subscribers must marshal to their own sync context.
+    /// </summary>
+    event Action<DriverHealthChanged>? SnapshotChanged;
 }