Implement role and user management enhancements

- Added MaxIpLimit to roles, allowing for the configuration of simultaneous IP limits for users.
- Updated role creation and update commands to include MaxIpLimit, ensuring proper handling in the application logic.
- Enhanced user management by introducing a DELETE endpoint for user accounts, with appropriate checks to prevent self-deletion.
- Updated documentation to reflect changes in role and user management, clarifying the new IP limit functionality and user deletion process.
- Adjusted related tests to cover new functionality and ensure robust validation of role and user management features.

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

@@ -0,0 +1,108 @@
+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.Configs;
+using PnvPanel.Domain.Inbounds;
+using PnvPanel.Domain.Nodes;
+using Xunit;
+
+namespace PnvPanel.Application.Tests.Admin.Users;
+
+public class DeleteUserCommandHandlerTests
+{
+    private readonly IIdentityService _identityService = Substitute.For<IIdentityService>();
+    private readonly IXuiPanelGateway _gateway = Substitute.For<IXuiPanelGateway>();
+    private readonly ITelegramNotifier _telegramNotifier = Substitute.For<ITelegramNotifier>();
+    private readonly ICurrentUser _currentUser = Substitute.For<ICurrentUser>();
+
+    [Fact]
+    public async Task Handle_WhenAdminTargetsSelf_ReturnsCannotDeleteSelfWithoutTouchingConfigs()
+    {
+        using var dbContext = InMemoryDbContextFactory.Create();
+        var adminId = Guid.NewGuid();
+        _currentUser.UserId.Returns(adminId);
+
+        var handler = new DeleteUserCommandHandler(dbContext, _identityService, _gateway, _telegramNotifier, _currentUser);
+
+        var result = await handler.Handle(new DeleteUserCommand(adminId), CancellationToken.None);
+
+        Assert.False(result.IsSuccess);
+        Assert.Equal(UserErrors.CannotDeleteSelf, result.Error);
+        await _identityService.DidNotReceive().DeleteUserAsync(Arg.Any<Guid>(), Arg.Any<CancellationToken>());
+    }
+
+    [Fact]
+    public async Task Handle_Success_RevokesConfigsWritesAuditNotifiesThenDeletesUser()
+    {
+        using var dbContext = InMemoryDbContextFactory.Create();
+        var userId = Guid.NewGuid();
+        var adminId = Guid.NewGuid();
+
+        var node = Node.Register("node-1", new Uri("https://node1.example.com"), new NodeCredentials("admin", "protected"), null);
+        var inbound = Inbound.FromRemote(node.Id, "1", VpnProtocol.Vless, "remark", 443);
+        var config = VpnConfig.Create(userId, inbound.Id, VpnProtocol.Vless, "my-config");
+        config.AssignRemoteClient("external-id");
+
+        dbContext.Nodes.Add(node);
+        dbContext.Inbounds.Add(inbound);
+        dbContext.VpnConfigs.Add(config);
+        await dbContext.SaveChangesAsync(CancellationToken.None);
+
+        _currentUser.UserId.Returns(adminId);
+        _gateway.RemoveClientAsync(Arg.Any<Node>(), Arg.Any<string>(), Arg.Any<string>(), Arg.Any<VpnProtocol>(), Arg.Any<CancellationToken>())
+            .Returns(Result.Success());
+        _identityService.DeleteUserAsync(userId, Arg.Any<CancellationToken>()).Returns(Result.Success());
+
+        var handler = new DeleteUserCommandHandler(dbContext, _identityService, _gateway, _telegramNotifier, _currentUser);
+
+        var result = await handler.Handle(new DeleteUserCommand(userId), CancellationToken.None);
+
+        Assert.True(result.IsSuccess);
+        Assert.Equal(ConfigStatus.Revoked, config.Status);
+
+        await _gateway.Received(1).RemoveClientAsync(
+            Arg.Is<Node>(n => n.Id == node.Id), inbound.RemoteInboundId, "external-id", config.Protocol, Arg.Any<CancellationToken>());
+        await _telegramNotifier.Received(1).NotifyUserAsync(userId, Arg.Any<string>(), Arg.Any<CancellationToken>());
+        await _identityService.Received(1).DeleteUserAsync(userId, Arg.Any<CancellationToken>());
+
+        var audit = Assert.Single(dbContext.AuditLogs.Local);
+        Assert.Equal("UserDeleted", audit.Action);
+        Assert.Equal(adminId, audit.ActorId);
+        Assert.Equal(userId.ToString(), audit.TargetId);
+    }
+
+    [Fact]
+    public async Task Handle_NoConfigs_SkipsGatewayButStillDeletesUser()
+    {
+        using var dbContext = InMemoryDbContextFactory.Create();
+        var userId = Guid.NewGuid();
+        _currentUser.UserId.Returns(Guid.NewGuid());
+        _identityService.DeleteUserAsync(userId, Arg.Any<CancellationToken>()).Returns(Result.Success());
+
+        var handler = new DeleteUserCommandHandler(dbContext, _identityService, _gateway, _telegramNotifier, _currentUser);
+
+        var result = await handler.Handle(new DeleteUserCommand(userId), CancellationToken.None);
+
+        Assert.True(result.IsSuccess);
+        await _gateway.DidNotReceive().RemoveClientAsync(
+            Arg.Any<Node>(), Arg.Any<string>(), Arg.Any<string>(), Arg.Any<VpnProtocol>(), Arg.Any<CancellationToken>());
+    }
+
+    [Fact]
+    public async Task Handle_WhenIdentityServiceFails_ReturnsFailure()
+    {
+        using var dbContext = InMemoryDbContextFactory.Create();
+        var userId = Guid.NewGuid();
+        _currentUser.UserId.Returns(Guid.NewGuid());
+        _identityService.DeleteUserAsync(userId, Arg.Any<CancellationToken>()).Returns(Result.Failure(UserErrors.NotFound));
+
+        var handler = new DeleteUserCommandHandler(dbContext, _identityService, _gateway, _telegramNotifier, _currentUser);
+
+        var result = await handler.Handle(new DeleteUserCommand(userId), CancellationToken.None);
+
+        Assert.False(result.IsSuccess);
+        Assert.Equal(UserErrors.NotFound, result.Error);
+    }
+}