Refactor client update handling to support nullable parameters for name and expiration

- Updated the `UpdateClientAsync` method in `IXuiPanelGateway` to accept nullable parameters for `name` and `expiresAt`, allowing for more flexible client management without unintended modifications.
- Adjusted the `BlockUserCommandHandler`, `UnblockUserCommandHandler`, and other related command handlers to utilize the new nullable parameters, ensuring that client names remain unchanged during block/unblock operations and that expiration dates are managed correctly.
- Enhanced the billing and configuration handling to reflect the new logic for managing client states based on expiration rather than enabling/disabling, improving reliability in client status management.
- Updated tests to cover the new behavior and ensure proper functionality across the application.

backend/src/PnvPanel.Infrastructure/BackgroundJobs/BillingService.cs

@@ -139,13 +139,18 @@ public sealed class BillingService(
 
             if (inbound is not null && node is not null)
             {
+                // Приостанавливаем через expiryTime в прошлом, а не enable:false — переключение enable
+                // ненадёжно останавливает уже установленные соединения на стороне Xray/панели (см.
+                // IXuiPanelGateway.UpdateClientAsync), просроченный expiryTime — надёжно и независимо
+                // от enable. name: null — не переименовываем клиента.
                 var updateResult = await gateway.UpdateClientAsync(
                     node,
                     inbound.RemoteInboundId,
                     config.ClientExternalId,
                     config.Protocol,
-                    config.Label ?? config.ClientEmail,
-                    enable: false,
+                    name: null,
+                    enable: null,
+                    expiresAt: DateTimeOffset.UtcNow.AddDays(-1),
                     cancellationToken
                 );
 

backend/src/PnvPanel.Infrastructure/Xui/XuiPanelGateway.cs

@@ -92,6 +92,7 @@ internal sealed class XuiPanelGateway(
         string clientEmail,
         string clientName,
         int limitIp,
+        DateTimeOffset? expiresAt,
         CancellationToken cancellationToken
     )
     {
@@ -105,7 +106,7 @@ internal sealed class XuiPanelGateway(
                 clientEmail,
                 ToRemoteProtocol(protocol),
                 limitIp == RoleQuota.Unlimited ? 0 : limitIp,
-                null
+                expiresAt
             );
             var result = await client.AddClientAsync(inboundRemoteId, request, cancellationToken);
             return Result.Success(result.ExternalClientId);
@@ -150,16 +151,17 @@ internal sealed class XuiPanelGateway(
         string inboundRemoteId,
         string clientExternalId,
         VpnProtocol protocol,
-        string name,
-        bool enable,
+        string? name,
+        bool? enable,
+        DateTimeOffset? expiresAt,
         CancellationToken cancellationToken
     )
     {
         try
         {
             var client = GetClient(node);
-            // deviceLimit: null — не трогаем то, что уже стоит на клиенте в панели (см. AddClientAsync).
-            var request = new UpdateClientRequest(null, null, enable, name);
+            // limitIp: null — не трогаем то, что уже стоит на клиенте в панели (см. AddClientAsync).
+            var request = new UpdateClientRequest(null, expiresAt, enable, name);
             await client.UpdateClientAsync(
                 inboundRemoteId,
                 clientExternalId,