test+docs(dashboard): assert hub policy under disable-login; correct warning/doc wording

src/ZB.MOM.WW.MxGateway.Server/Dashboard/DashboardServiceCollectionExtensions.cs

@@ -73,7 +73,8 @@ public static class DashboardServiceCollectionExtensions
                 DashboardAuthenticationDefaults.AuthenticationScheme,
                 _ => { });
 
-            // Loud, once-at-startup warning (emitted when GatewayOptions is first resolved).
+            // Loud warning, emitted on first resolution of GatewayOptions (i.e. on the first
+            // request/options access, not guaranteed at process start). Dev-only safety notice.
             services.AddOptions<GatewayOptions>().PostConfigure<ILoggerFactory>((gatewayOptions, loggerFactory) =>
                 loggerFactory
                     .CreateLogger("ZB.MOM.WW.MxGateway.Server.Dashboard.DisableLogin")

src/ZB.MOM.WW.MxGateway.Tests/Gateway/Dashboard/DashboardDisableLoginTests.cs

@@ -53,5 +53,7 @@ public sealed class DashboardDisableLoginTests
             user, resource: null, DashboardAuthenticationDefaults.AdminPolicy)).Succeeded);
         Assert.True((await authorization.AuthorizeAsync(
             user, resource: null, DashboardAuthenticationDefaults.ViewerPolicy)).Succeeded);
+        Assert.True((await authorization.AuthorizeAsync(
+            user, resource: null, DashboardAuthenticationDefaults.HubClientsPolicy)).Succeeded);
     }
 }