feat(infra): configure beta deployment to Test environment with hardened security and feature flags

src/NexusReader.UI.Shared/Pages/Account/Register.razor

@@ -7,6 +7,7 @@
 @inject IIdentityService IdentityService
 @inject NavigationManager NavigationManager
 @inject IJSRuntime JS
+@inject IConfiguration Configuration
 
 <div class="login-page-container">
     <div class="mesh-bg"></div>
@@ -81,6 +82,15 @@
     private string? _errorMessage;
     private bool _isSubmitting;
 
+    protected override void OnInitialized()
+    {
+        var allowRegistration = Configuration.GetValue<bool?>("Features:AllowRegistration") ?? true;
+        if (!allowRegistration)
+        {
+            NavigationManager.NavigateTo("/account/login?error=RegistrationDisabled", replace: true);
+        }
+    }
+
     private async Task HandleRegister()
     {
         _isSubmitting = true;