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);