feat(index): add TwentyCard credit promo section and integrate portal link

- Introduced a new promotional section for TwentyCard credit on the landing page, featuring details about the service and a button to access the TwentyCard portal.
- Updated the Index.razor.cs file to retrieve the portal URL from configuration and implemented the logic to open the portal in a new tab.
- Enhanced site.css with styling specific to the TwentyCard promo box.

These changes enhance user engagement by promoting the TwentyCard credit option and providing easy access to its portal.

src/FrontOffice.Main/Pages/Index.razor.cs

@@ -1,5 +1,6 @@
 using FrontOffice.Main.Utilities;
 using Microsoft.AspNetCore.Components;
+using Microsoft.Extensions.Configuration;
 using Microsoft.JSInterop;
 using MudBlazor;
 
@@ -16,8 +17,10 @@ public partial class Index : IDisposable
     [Inject] private DiscountCartService DiscountCart { get; set; } = default!;
     [Inject] private GuestActionGate GuestGate { get; set; } = default!;
     [Inject] private VATService VAT { get; set; } = default!;
+    [Inject] private IConfiguration Configuration { get; set; } = default!;
 
     private bool _isAuthenticated;
+    private string _twentyCardPortalUrl = string.Empty;
 
     // ── CMS page data ──
     private PageSettingsDto? _pageData;
@@ -49,6 +52,7 @@ public partial class Index : IDisposable
     {
         MainService.OnChangeHandler += OnStateChanged;
         _isAuthenticated = await AuthService.IsAuthenticatedAsync();
+        _twentyCardPortalUrl = Configuration["TwentyCard:CreditPortalUrl"] ?? string.Empty;
 
         // Load landing page settings from CMS
         try
@@ -298,6 +302,12 @@ public partial class Index : IDisposable
         Navigation.NavigateTo(RouteConstants.Registration.Wizard);
     }
 
+    private async Task OpenTwentyCardPortal()
+    {
+        if (string.IsNullOrWhiteSpace(_twentyCardPortalUrl)) return;
+        await JS.InvokeVoidAsync("open", _twentyCardPortalUrl, "_blank");
+    }
+
     private void NavigateToPost(string slug)
     {
         Navigation.NavigateTo($"/blog/{slug}");