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.Host/Program.cs

@@ -122,6 +122,11 @@ if (hasAdmin)
     // Auth + AdminUI surface only mounted on admin-role nodes. Driver-only nodes have no UI.
     builder.Services.AddOtOpcUaAuth(builder.Configuration);
     builder.Services.AddAdminUI();
+    // Test Connect probes back the AdminUI driver pages. The admin-operations singleton (role-pinned
+    // to admin) resolves IEnumerable<IDriverProbe>, so admin-only nodes — which skip the hasDriver
+    // block above — must wire the probe set here too, or every Test Connect returns "No probe
+    // registered". Idempotent on fused admin,driver nodes (TryAddEnumerable de-dups).
+    builder.Services.AddOtOpcUaDriverProbes();
     // Flow AuthenticationState through cascading parameters so <AuthorizeView/> works
     // inside interactive components (NavSidebar's session block).
     builder.Services.AddCascadingAuthenticationState();