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/Auth/GetCurrentUserQueryHandlerTests.cs

@@ -2,6 +2,7 @@ using NSubstitute;
 using PnvPanel.Application.Auth;
 using PnvPanel.Application.Auth.Me;
 using PnvPanel.Application.Common.Interfaces;
+using PnvPanel.Application.Common.Models;
 using PnvPanel.Application.Tests.TestSupport;
 using Xunit;
 
@@ -40,7 +41,7 @@ public class GetCurrentUserQueryHandlerTests
     public async Task Handle_AuthenticatedWithProfile_ReturnsCurrentUserDto()
     {
         var userId = Guid.NewGuid();
-        var profile = new CurrentUserProfile(userId, "alice", Guid.NewGuid(), "user", true, false, 3, "sub-token");
+        var profile = new CurrentUserProfile(userId, "alice", Guid.NewGuid(), "user", true, false, 3, RoleQuota.Unlimited, "sub-token");
         _identityService.GetProfileAsync(userId, Arg.Any<CancellationToken>()).Returns(profile);
         _identityService.GetTelegramLinkInfoAsync(userId, Arg.Any<CancellationToken>())
             .Returns(new TelegramLinkInfo(true, 42, "alice_tg"));