fix: validate discount wallet balance before applying discount in PlaceOrderCommandHandler

Bug: when buying from discount shop, DiscountBalance was deducted from DB
but no UserWalletChangeLog was created — making it invisible in wallet history.
Same issue existed for discount wallet top-up (charge).

Fixed in 3 handlers:
- PlaceOrderCommandHandler (fully paid by discount balance path)
- CompleteOrderPaymentCommandHandler (gateway + discount balance path)
- VerifyDiscountWalletChargeCommandHandler (discount wallet charge)

src/CMSMicroservice.Application/DiscountShopCQ/Commands/CompleteOrderPayment/CompleteOrderPaymentCommandHandler.cs

@@ -62,9 +62,23 @@ public class CompleteOrderPaymentCommandHandler : IRequestHandler<CompleteOrderP
             var userWallet = await _context.UserWallets
                 .FirstOrDefaultAsync(w => w.UserId == order.UserId, cancellationToken);
 
-            if (userWallet != null)
+            if (userWallet != null && order.DiscountBalanceUsed > 0)
             {
                 userWallet.DiscountBalance -= order.DiscountBalanceUsed;
+
+                // ثبت لاگ تغییرات کیف پول
+                _context.UserWalletChangeLogs.Add(new Domain.Entities.UserWalletChangeLog
+                {
+                    WalletId = userWallet.Id,
+                    CurrentBalance = userWallet.Balance,
+                    ChangeValue = 0,
+                    CurrentNetworkBalance = userWallet.NetworkBalance,
+                    ChangeNerworkValue = 0,
+                    CurrentDiscountBalance = userWallet.DiscountBalance,
+                    ChangeDiscountValue = -order.DiscountBalanceUsed,
+                    IsIncrease = false,
+                    RefrenceId = transaction.Id
+                });
             }
 
             // تایید فروش و کسر موجودی از طریق InventoryService

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

@@ -111,7 +111,18 @@ public class PlaceOrderCommandHandler : IRequestHandler<PlaceOrderCommand, Place
 
         // Always apply maximum possible discount (100%) — user cannot choose less
         var maxDiscountBalanceUsable = totalDiscountAmount;
-        var actualDiscountBalanceUsed = Math.Min(maxDiscountBalanceUsable, userWallet.DiscountBalance);
+
+        // بررسی کافی بودن موجودی کیف پول اعتباری (تخفیفی)
+        if (userWallet.DiscountBalance < maxDiscountBalanceUsable)
+        {
+            return new PlaceOrderResponseDto
+            {
+                Success = false,
+                Message = $"موجودی کیف پول اعتباری کافی نیست. مبلغ مورد نیاز: {maxDiscountBalanceUsable:N0} ریال، موجودی شما: {userWallet.DiscountBalance:N0} ریال"
+            };
+        }
+
+        var actualDiscountBalanceUsed = maxDiscountBalanceUsable;
 
         _logger.LogInformation(
             "Discount auto-applied: max allowed={MaxAllowed}, wallet balance={WalletBalance}, used={Used}",
@@ -263,9 +274,25 @@ public class PlaceOrderCommandHandler : IRequestHandler<PlaceOrderCommand, Place
 
             var walletForDeduct = await _context.UserWallets
                 .FirstOrDefaultAsync(w => w.UserId == request.UserId, cancellationToken);
-            if (walletForDeduct != null)
+            if (walletForDeduct != null && actualDiscountBalanceUsed > 0)
+            {
                 walletForDeduct.DiscountBalance -= actualDiscountBalanceUsed;
 
+                // ثبت لاگ تغییرات کیف پول
+                _context.UserWalletChangeLogs.Add(new Domain.Entities.UserWalletChangeLog
+                {
+                    WalletId = walletForDeduct.Id,
+                    CurrentBalance = walletForDeduct.Balance,
+                    ChangeValue = 0,
+                    CurrentNetworkBalance = walletForDeduct.NetworkBalance,
+                    ChangeNerworkValue = 0,
+                    CurrentDiscountBalance = walletForDeduct.DiscountBalance,
+                    ChangeDiscountValue = -actualDiscountBalanceUsed,
+                    IsIncrease = false,
+                    RefrenceId = transaction.Id
+                });
+            }
+
             foreach (var cartItem in cartItems)
             {
                 await _inventoryService.ConfirmSaleAsync(

src/CMSMicroservice.Application/WalletCQ/Commands/VerifyDiscountWalletCharge/VerifyDiscountWalletChargeCommandHandler.cs

@@ -114,6 +114,21 @@ public class VerifyDiscountWalletChargeCommandHandler
             _context.Transactions.Add(transaction);
             await _context.SaveChangesAsync(cancellationToken);
 
+            // ثبت لاگ تغییرات کیف پول (بعد از ایجاد Transaction برای داشتن TransactionId)
+            _context.UserWalletChangeLogs.Add(new Domain.Entities.UserWalletChangeLog
+            {
+                WalletId = wallet.Id,
+                CurrentBalance = wallet.Balance,
+                ChangeValue = 0,
+                CurrentNetworkBalance = wallet.NetworkBalance,
+                ChangeNerworkValue = 0,
+                CurrentDiscountBalance = wallet.DiscountBalance,
+                ChangeDiscountValue = request.Amount,
+                IsIncrease = true,
+                RefrenceId = transaction.Id
+            });
+            await _context.SaveChangesAsync(cancellationToken);
+
             // لینک PaymentTransaction به Transaction داخلی
             if (paymentTx != null)
             {