feat: add VAT display to all DiscountStore pages — Products (note), ProductDetail (breakdown), Cart (summary line), Checkout (refactor to VATService), OrderDetail (financial summary)

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

@@ -10,6 +10,7 @@ public partial class Checkout
     [Inject] private DiscountCartService DiscountCart { get; set; } = default!;
     [Inject] private DiscountOrderService DiscountOrderService { get; set; } = default!;
     [Inject] private UserAddressContract.UserAddressContractClient UserAddressContract { get; set; } = default!;
+    [Inject] private VATService VAT { get; set; } = default!;
 
     private List<CustomerAddressModel> _addresses = new();
     private CustomerAddressModel? _selectedAddress;
@@ -18,13 +19,11 @@ public partial class Checkout
     private string? _notes;
     private bool _placing;
 
-    private const decimal VAT_RATE = 0.10m;
-
     /// <summary>مبلغ درگاه قبل از مالیات (جمع کل - اعتبار)</summary>
     private long NetGatewayAmount => DiscountCart.TotalPrice - DiscountCart.TotalDiscount;
 
-    /// <summary>مالیات بر ارزش افزوده ۱۰٪</summary>
-    private long VatAmount => (long)(NetGatewayAmount * VAT_RATE);
+    /// <summary>مالیات بر ارزش افزوده</summary>
+    private long VatAmount => VAT.CalculateVAT(NetGatewayAmount);
 
     /// <summary>مبلغ نهایی قابل پرداخت (شامل VAT)</summary>
     private long FinalGatewayAmount => NetGatewayAmount + VatAmount;
@@ -33,6 +32,7 @@ public partial class Checkout
 
     protected override async Task OnInitializedAsync()
     {
+        await VAT.LoadAsync();
         await DiscountCart.EnsureInitializedAsync();
         await LoadAddresses();
     }