Implement billing status notification and enhance user management integration

- Added `NotifyBillingStatusChangedAsync` method to `IRealtimeNotifier` for notifying clients about changes in billing status.
- Updated `BillingConfigResumer` to call the new notification method after modifying billing configurations, ensuring users receive real-time updates.
- Enhanced `ListUsersQueryHandler` to include a `BillingPendingReview` property in `UserSummaryDto`, indicating if a user has a pending payment request awaiting confirmation.
- Refactored various command handlers to utilize `AdvisoryLock` for managing concurrent requests, preventing race conditions in billing operations.
- Updated tests to cover new notification behaviors and ensure proper functionality in billing status management.

backend/tests/PnvPanel.Application.Tests/Billing/CreatePaymentRequest/CreatePaymentRequestCommandHandlerTests.cs

@@ -150,6 +150,9 @@ public class CreatePaymentRequestCommandHandlerTests
     {
         using var dbContext = InMemoryDbContextFactory.Create();
         var userId = Guid.NewGuid();
+        var pricing = PricingSettings.CreateDefault();
+        pricing.Update(500, 450, 400);
+        dbContext.PricingSettings.Add(pricing);
         dbContext.PaymentRequests.Add(PaymentRequest.Create(userId, PaymentPeriod.Quarter, 1000));
         await dbContext.SaveChangesAsync(CancellationToken.None);
 

backend/tests/PnvPanel.Application.Tests/Billing/MarkPaymentSent/MarkPaymentSentCommandHandlerTests.cs

@@ -16,13 +16,14 @@ public class MarkPaymentSentCommandHandlerTests
 {
     private readonly IIdentityService _identityService = Substitute.For<IIdentityService>();
     private readonly IXuiPanelGateway _gateway = Substitute.For<IXuiPanelGateway>();
+    private readonly IRealtimeNotifier _notifier = Substitute.For<IRealtimeNotifier>();
     private readonly ITelegramNotifier _telegramNotifier = Substitute.For<ITelegramNotifier>();
     private readonly ILogger<MarkPaymentSentCommandHandler> _logger = Substitute.For<
         ILogger<MarkPaymentSentCommandHandler>
     >();
 
     private MarkPaymentSentCommandHandler CreateHandler(IAppDbContext dbContext, Guid userId) =>
-        new(dbContext, _identityService, _gateway, _telegramNotifier, FakeCurrentUser.Authenticated(userId, "alice"), _logger);
+        new(dbContext, _identityService, _gateway, _notifier, _telegramNotifier, FakeCurrentUser.Authenticated(userId, "alice"), _logger);
 
     private static CurrentUserProfile Profile(Guid userId, DateTimeOffset? paidUntil) =>
         new(
@@ -139,6 +140,7 @@ public class MarkPaymentSentCommandHandlerTests
                 Arg.Is<DateTimeOffset?>(d => d > DateTimeOffset.UtcNow),
                 Arg.Any<CancellationToken>()
             );
+        await _notifier.Received(1).NotifyBillingStatusChangedAsync(userId, Arg.Any<CancellationToken>());
     }
 
     [Fact]