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/Admin/Billing/ConfirmPaymentRequestCommandHandlerTests.cs

@@ -220,6 +220,7 @@ public class ConfirmPaymentRequestCommandHandlerTests
                 Arg.Is<DateTimeOffset?>(d => d == activeConfig.ExpiresAt),
                 Arg.Any<CancellationToken>()
             );
+        await _notifier.Received(1).NotifyBillingStatusChangedAsync(userId, Arg.Any<CancellationToken>());
     }
 
     [Fact]

backend/tests/PnvPanel.Application.Tests/Admin/Billing/RejectPaymentRequestCommandHandlerTests.cs

@@ -147,6 +147,8 @@ public class RejectPaymentRequestCommandHandlerTests
                 Arg.Any<DateTimeOffset?>(),
                 Arg.Any<CancellationToken>()
             );
+        // Фронт (/billing) должен узнать о смене статуса сразу, не дожидаясь опроса.
+        await _notifier.Received(1).NotifyBillingStatusChangedAsync(userId, Arg.Any<CancellationToken>());
     }
 
     [Fact]

backend/tests/PnvPanel.Application.Tests/Admin/Support/CloseTicketCommandHandlerTests.cs

@@ -1,6 +1,7 @@
 using NSubstitute;
 using PnvPanel.Application.Admin.Support;
 using PnvPanel.Application.Common.Interfaces;
+using PnvPanel.Application.Support;
 using PnvPanel.Application.Tests.TestSupport;
 using PnvPanel.Domain.Support;
 using Xunit;
@@ -65,4 +66,31 @@ public class CloseTicketCommandHandlerTests
         Assert.True(result.IsSuccess);
         Assert.Equal(TicketStatus.Closed, ticket.Status);
     }
+
+    [Fact]
+    public async Task Handle_WhenExtensionRequest_ReturnsOnlyBugReportCanBeClosedDirectly()
+    {
+        using var dbContext = InMemoryDbContextFactory.Create();
+        var userId = Guid.NewGuid();
+        var ticket = SupportTicket.CreateExtensionRequest(userId, 30);
+        dbContext.SupportTickets.Add(ticket);
+        await dbContext.SaveChangesAsync(CancellationToken.None);
+
+        var currentUser = FakeCurrentUser.Authenticated(Guid.NewGuid(), "admin");
+        var handler = new CloseTicketCommandHandler(
+            dbContext,
+            _notifier,
+            _telegramNotifier,
+            currentUser
+        );
+
+        var result = await handler.Handle(
+            new CloseTicketCommand(ticket.Id),
+            CancellationToken.None
+        );
+
+        Assert.False(result.IsSuccess);
+        Assert.Equal(SupportErrors.OnlyBugReportCanBeClosedDirectly, result.Error);
+        Assert.Equal(TicketStatus.Open, ticket.Status);
+    }
 }

backend/tests/PnvPanel.Application.Tests/Admin/Support/ResolveTicketCommandHandlerTests.cs

@@ -1,6 +1,7 @@
 using NSubstitute;
 using PnvPanel.Application.Admin.Support;
 using PnvPanel.Application.Common.Interfaces;
+using PnvPanel.Application.Support;
 using PnvPanel.Application.Tests.TestSupport;
 using PnvPanel.Domain.Support;
 using Xunit;
@@ -65,4 +66,34 @@ public class ResolveTicketCommandHandlerTests
         Assert.True(result.IsSuccess);
         Assert.Equal(TicketStatus.Resolved, ticket.Status);
     }
+
+    [Fact]
+    public async Task Handle_WhenRoleRequest_ReturnsOnlyBugReportCanBeResolvedDirectly()
+    {
+        // Заявку на роль/продление можно решить только через Approve/Reject — Resolve обходил бы
+        // одобрение (роль/продление так и не назначились бы), см. CLAUDE.md.
+        using var dbContext = InMemoryDbContextFactory.Create();
+        var userId = Guid.NewGuid();
+        var roleId = Guid.NewGuid();
+        var ticket = SupportTicket.CreateRoleRequestForExistingRole(userId, roleId);
+        dbContext.SupportTickets.Add(ticket);
+        await dbContext.SaveChangesAsync(CancellationToken.None);
+
+        var currentUser = FakeCurrentUser.Authenticated(Guid.NewGuid(), "admin");
+        var handler = new ResolveTicketCommandHandler(
+            dbContext,
+            _notifier,
+            _telegramNotifier,
+            currentUser
+        );
+
+        var result = await handler.Handle(
+            new ResolveTicketCommand(ticket.Id),
+            CancellationToken.None
+        );
+
+        Assert.False(result.IsSuccess);
+        Assert.Equal(SupportErrors.OnlyBugReportCanBeResolvedDirectly, result.Error);
+        Assert.Equal(TicketStatus.Open, ticket.Status);
+    }
 }

backend/tests/PnvPanel.Application.Tests/Admin/Users/ListUsersQueryHandlerTests.cs

@@ -0,0 +1,81 @@
+using NSubstitute;
+using PnvPanel.Application.Admin.Users;
+using PnvPanel.Application.Common.Interfaces;
+using PnvPanel.Application.Common.Models;
+using PnvPanel.Application.Tests.TestSupport;
+using PnvPanel.Domain.Billing;
+using Xunit;
+
+namespace PnvPanel.Application.Tests.Admin.Users;
+
+public class ListUsersQueryHandlerTests
+{
+    private readonly IIdentityService _identityService = Substitute.For<IIdentityService>();
+
+    private static UserSummaryDto Summary(Guid id) =>
+        new(id, "alice", "premium", true, false, DateTimeOffset.UtcNow, true, DateTimeOffset.UtcNow.AddDays(-1));
+
+    [Fact]
+    public async Task Handle_WhenUserHasAwaitingConfirmationSubscriptionRequest_SetsBillingPendingReview()
+    {
+        using var dbContext = InMemoryDbContextFactory.Create();
+        var userId = Guid.NewGuid();
+        var request = PaymentRequest.Create(userId, PaymentPeriod.Quarter, 1000);
+        request.MarkPaymentSent();
+        dbContext.PaymentRequests.Add(request);
+        await dbContext.SaveChangesAsync(CancellationToken.None);
+
+        _identityService
+            .ListUsersAsync(1, 20, null, Arg.Any<CancellationToken>())
+            .Returns(new PagedList<UserSummaryDto>([Summary(userId)], 1, 1, 20));
+
+        var handler = new ListUsersQueryHandler(_identityService, dbContext);
+
+        var result = await handler.Handle(new ListUsersQuery(1, 20, null), CancellationToken.None);
+
+        Assert.True(result.IsSuccess);
+        Assert.True(result.Value.Items.Single().BillingPendingReview);
+    }
+
+    [Fact]
+    public async Task Handle_WhenNoPendingRequest_LeavesBillingPendingReviewFalse()
+    {
+        using var dbContext = InMemoryDbContextFactory.Create();
+        var userId = Guid.NewGuid();
+
+        _identityService
+            .ListUsersAsync(1, 20, null, Arg.Any<CancellationToken>())
+            .Returns(new PagedList<UserSummaryDto>([Summary(userId)], 1, 1, 20));
+
+        var handler = new ListUsersQueryHandler(_identityService, dbContext);
+
+        var result = await handler.Handle(new ListUsersQuery(1, 20, null), CancellationToken.None);
+
+        Assert.True(result.IsSuccess);
+        Assert.False(result.Value.Items.Single().BillingPendingReview);
+    }
+
+    [Fact]
+    public async Task Handle_WhenPendingRequestIsRoleChangeTopUp_LeavesBillingPendingReviewFalse()
+    {
+        // RoleChangeTopUp — доплата за смену роли, не подписка; не должна показывать пользователя
+        // как "оплата на проверке" в админке (см. CLAUDE.md про Kind).
+        using var dbContext = InMemoryDbContextFactory.Create();
+        var userId = Guid.NewGuid();
+        var request = PaymentRequest.CreateRoleChangeTopUp(userId, 500);
+        request.MarkPaymentSent();
+        dbContext.PaymentRequests.Add(request);
+        await dbContext.SaveChangesAsync(CancellationToken.None);
+
+        _identityService
+            .ListUsersAsync(1, 20, null, Arg.Any<CancellationToken>())
+            .Returns(new PagedList<UserSummaryDto>([Summary(userId)], 1, 1, 20));
+
+        var handler = new ListUsersQueryHandler(_identityService, dbContext);
+
+        var result = await handler.Handle(new ListUsersQuery(1, 20, null), CancellationToken.None);
+
+        Assert.True(result.IsSuccess);
+        Assert.False(result.Value.Items.Single().BillingPendingReview);
+    }
+}