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/LoginCommandHandlerTests.cs

@@ -20,7 +20,9 @@ public class LoginCommandHandlerTests
     {
         var userId = Guid.NewGuid();
         var authUser = new AuthenticatedUser(userId, "alice", "user");
-        var profile = new CurrentUserProfile(userId, "alice", Guid.NewGuid(), "user", IsActivated: true, IsBlocked: false, MaxConfigs: 3, SubscriptionToken: "sub-token");
+        var profile = new CurrentUserProfile(
+            userId, "alice", Guid.NewGuid(), "user", IsActivated: true, IsBlocked: false, MaxConfigs: 3,
+            MaxIpLimit: RoleQuota.Unlimited, SubscriptionToken: "sub-token");
 
         _identityService.ValidateCredentialsAsync("alice", "P@ssw0rd", Arg.Any<CancellationToken>())
             .Returns(Result.Success(authUser));