feat(payment): add per-user in-memory lock for gateway operations

Introduce IUserPaymentLock to serialize payment initiate and verify flows
per user, preventing concurrent duplicate gateway requests across services.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/CMSMicroservice.WebApi/Services/UserWalletService.cs

@@ -13,6 +13,7 @@ using CMSMicroservice.Application.UserWalletCQ.Queries.GetCustomerWalletHistory;
 using CMSMicroservice.Application.UserWalletCQ.Queries.GetCustomerWithdrawals;
 using CMSMicroservice.Application.UserWalletCQ.Queries.GetCustomerWithdrawalSettings;
 using CMSMicroservice.Application.Common.Interfaces;
+using CMSMicroservice.Application.Common.Exceptions;
 using CMSMicroservice.Domain.Common;
 using CMSMicroservice.Domain.Enums;
 using Grpc.Core;
@@ -184,18 +185,29 @@ public class UserWalletService : UserWalletContract.UserWalletContractBase
     {
         var userId = GetCurrentUserId();
 
-        var result = await _sender.Send(new ChargeMagicWalletCommand
+        try
         {
-            UserId = userId,
-            Amount = request.Amount
-        }, context.CancellationToken);
+            var result = await _sender.Send(new ChargeMagicWalletCommand
+            {
+                UserId = userId,
+                Amount = request.Amount
+            }, context.CancellationToken);
 
-        return new InitiateMagicChargeResponse
+            return new InitiateMagicChargeResponse
+            {
+                IsSuccess = result.IsSuccess,
+                GatewayUrl = result.GatewayUrl ?? "",
+                ErrorMessage = result.ErrorMessage ?? ""
+            };
+        }
+        catch (PaymentInProgressException ex)
         {
-            IsSuccess = result.IsSuccess,
-            GatewayUrl = result.GatewayUrl ?? "",
-            ErrorMessage = result.ErrorMessage ?? ""
-        };
+            return new InitiateMagicChargeResponse
+            {
+                IsSuccess = false,
+                ErrorMessage = ex.Message
+            };
+        }
     }
 
     // ============= Discount Wallet Methods =============
@@ -205,18 +217,29 @@ public class UserWalletService : UserWalletContract.UserWalletContractBase
     {
         var userId = GetCurrentUserId();
 
-        var result = await _sender.Send(new ChargeDiscountWalletCommand
+        try
         {
-            UserId = userId,
-            Amount = request.Amount
-        }, context.CancellationToken);
+            var result = await _sender.Send(new ChargeDiscountWalletCommand
+            {
+                UserId = userId,
+                Amount = request.Amount
+            }, context.CancellationToken);
 
-        return new InitiateDiscountChargeResponse
+            return new InitiateDiscountChargeResponse
+            {
+                IsSuccess = result.IsSuccess,
+                GatewayUrl = result.GatewayUrl ?? "",
+                ErrorMessage = result.ErrorMessage ?? ""
+            };
+        }
+        catch (PaymentInProgressException ex)
         {
-            IsSuccess = result.IsSuccess,
-            GatewayUrl = result.GatewayUrl ?? "",
-            ErrorMessage = result.ErrorMessage ?? ""
-        };
+            return new InitiateDiscountChargeResponse
+            {
+                IsSuccess = false,
+                ErrorMessage = ex.Message
+            };
+        }
     }
 
     // ============= Wallet Verify Methods =============