fix: force 100% discount in PlaceOrder — ignore client DiscountBalanceToUse, always use max

src/CMSMicroservice.Application/DiscountShopCQ/Commands/PlaceOrder/PlaceOrderCommandHandler.cs

@@ -109,19 +109,13 @@ public class PlaceOrderCommandHandler : IRequestHandler<PlaceOrderCommand, Place
             });
         }
 
-        // Validate discount balance usage
+        // Always apply maximum possible discount (100%) — user cannot choose less
         var maxDiscountBalanceUsable = totalDiscountAmount;
-        var actualDiscountBalanceUsed = Math.Min(request.DiscountBalanceToUse, maxDiscountBalanceUsable);
-        actualDiscountBalanceUsed = Math.Min(actualDiscountBalanceUsed, userWallet.DiscountBalance);
+        var actualDiscountBalanceUsed = Math.Min(maxDiscountBalanceUsable, userWallet.DiscountBalance);
 
-        if (actualDiscountBalanceUsed < request.DiscountBalanceToUse)
-        {
-            return new PlaceOrderResponseDto
-            {
-                Success = false,
-                Message = $"موجودی تخفیف کافی نیست. حداکثر قابل استفاده: {maxDiscountBalanceUsable:N0} تومان، موجودی شما: {userWallet.DiscountBalance:N0} تومان"
-            };
-        }
+        _logger.LogInformation(
+            "Discount auto-applied: max allowed={MaxAllowed}, wallet balance={WalletBalance}, used={Used}",
+            maxDiscountBalanceUsable, userWallet.DiscountBalance, actualDiscountBalanceUsed);
 
         var gatewayAmountRequired = totalAmount - actualDiscountBalanceUsed;