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.

tests/Server/ZB.MOM.WW.OtOpcUa.AdminUI.Tests/DriverStatusSnapshotStoreTests.cs

@@ -0,0 +1,59 @@
+using Shouldly;
+using Xunit;
+using ZB.MOM.WW.OtOpcUa.AdminUI.Hubs;
+using ZB.MOM.WW.OtOpcUa.Commons.Messages.Drivers;
+
+namespace ZB.MOM.WW.OtOpcUa.AdminUI.Tests;
+
+/// <summary>
+///     Covers the in-process push contract the Blazor Server <c>DriverStatusPanel</c> relies on:
+///     <see cref="IDriverStatusSnapshotStore.SnapshotChanged"/> fires on every
+///     <see cref="IDriverStatusSnapshotStore.Upsert"/>, and <c>TryGet</c> returns the latest.
+///     The panel subscribes to this store directly instead of opening a self-targeted SignalR
+///     connection (which a server-side component can't reach behind a reverse proxy).
+/// </summary>
+public sealed class DriverStatusSnapshotStoreTests
+{
+    private static DriverHealthChanged Snap(string instance, string state = "Healthy") =>
+        new("MAIN", instance, state, null, null, 0, new DateTime(2026, 5, 29, 0, 0, 0, DateTimeKind.Utc));
+
+    [Fact]
+    public void Upsert_raises_SnapshotChanged_with_the_stored_snapshot()
+    {
+        var store = new InMemoryDriverStatusSnapshotStore();
+        var received = new List<DriverHealthChanged>();
+        store.SnapshotChanged += received.Add;
+
+        var snap = Snap("drv-1", "Faulted");
+        store.Upsert(snap);
+
+        received.Count.ShouldBe(1);
+        received[0].ShouldBeSameAs(snap);
+    }
+
+    [Fact]
+    public void Upsert_then_TryGet_returns_the_latest_snapshot()
+    {
+        var store = new InMemoryDriverStatusSnapshotStore();
+        store.Upsert(Snap("drv-1", "Healthy"));
+        store.Upsert(Snap("drv-1", "Degraded"));
+
+        store.TryGet("drv-1", out var latest).ShouldBeTrue();
+        latest.State.ShouldBe("Degraded");
+    }
+
+    [Fact]
+    public void Unsubscribed_handler_stops_receiving_after_removal()
+    {
+        var store = new InMemoryDriverStatusSnapshotStore();
+        var count = 0;
+        void Handler(DriverHealthChanged _) => count++;
+
+        store.SnapshotChanged += Handler;
+        store.Upsert(Snap("drv-1"));
+        store.SnapshotChanged -= Handler;
+        store.Upsert(Snap("drv-1"));
+
+        count.ShouldBe(1);
+    }
+}