refactor(checkout): simplify address management and improve package selection logic

- Removed the address selection UI and related logic from the Checkout page to streamline the user experience.
- Updated the payment validation to only require package selection, enhancing clarity for users.
- Adjusted the loading of addresses in related components based on user authentication status, ensuring addresses are only loaded when available.

These changes improve the overall usability of the checkout process by focusing on essential selections and reducing unnecessary complexity.

src/FrontOffice.Main/Pages/DiscountStore/Checkout.razor.cs

@@ -40,7 +40,11 @@ public partial class Checkout
         }
         await VAT.LoadAsync();
         await DiscountCart.EnsureInitializedAsync();
-        await LoadAddresses();
+        var userInfo = await AuthService.GetUserAuthInfo();
+        if (userInfo.HasAddress)
+            await LoadAddresses();
+        else
+            _addresses = new();
     }
 
     private async Task LoadAddresses()