feat: ChargeDiscountWallet UI - page, route, client method & wallet link

- Add ChargeDiscountWallet.razor page with charge form and preset amounts
- Add ChargeDiscountWallet.razor.cs code-behind with gateway redirect logic
- Add InitiateDiscountChargeAsync client method in WalletService
- Add ChargeDiscountWallet route constant
- Add charge button link on main Wallet page

src/FrontOffice.Main/Utilities/RouteConstants.cs

@@ -23,6 +23,7 @@ public static class RouteConstants
         public const string Tree = "/profile/tree";
         public const string Wallet = "/profile/wallet";
         public const string MagicWallet = "/profile/magic-wallet";
+        public const string ChargeDiscountWallet = "/profile/charge-discount-wallet";
         public const string WithdrawalRequests = "/profile/withdrawal-requests";
     }
 

src/FrontOffice.Main/Utilities/WalletService.cs

@@ -243,6 +243,26 @@ public class WalletService
         }
     }
 
+    public async Task<(bool Success, string? GatewayUrl, string? Error)> InitiateDiscountChargeAsync(long amount)
+    {
+        try
+        {
+            var response = await _client.InitiateDiscountChargeAsync(new InitiateDiscountChargeRequest
+            {
+                Amount = amount
+            });
+
+            if (response.IsSuccess)
+                return (true, response.GatewayUrl, null);
+
+            return (false, null, response.ErrorMessage);
+        }
+        catch (Grpc.Core.RpcException ex)
+        {
+            return (false, null, ex.Status.Detail ?? "خطا در ارتباط با سرور");
+        }
+    }
+
     public int GetWalletMode()
     {
         try