Implement activation checks across various commands and queries

- Introduced `IRequiresActivation` interface to enforce activation requirements for multiple commands and queries, ensuring that only activated users can create, edit, or access configurations, news, and applications.
- Updated the `RequireActivationBehavior` to handle activation checks uniformly, returning appropriate errors for unauthenticated or inactive users.
- Enhanced error handling by adding `NotActivated` error to provide clear feedback for users attempting to access restricted features.
- Updated documentation to reflect the new activation requirements and their implications on user access and functionality.

backend/tests/PnvPanel.Application.Tests/Common/Behaviors/RequireActivationBehaviorTests.cs

@@ -0,0 +1,85 @@
+using NSubstitute;
+using PnvPanel.Application.Auth;
+using PnvPanel.Application.Common.Behaviors;
+using PnvPanel.Application.Common.Interfaces;
+using PnvPanel.Application.Common.Messaging;
+using PnvPanel.Application.Common.Models;
+using Xunit;
+
+namespace PnvPanel.Application.Tests.Common.Behaviors;
+
+public class RequireActivationBehaviorTests
+{
+    private sealed record DummyRequest : IRequiresActivation;
+
+    private readonly ICurrentUser _currentUser = Substitute.For<ICurrentUser>();
+    private readonly IIdentityService _identityService = Substitute.For<IIdentityService>();
+
+    private RequireActivationBehavior<DummyRequest, Result<string>> CreateBehavior() => new(_currentUser, _identityService);
+
+    private static CurrentUserProfile CreateProfile(Guid userId, bool isActivated) =>
+        new(userId, "alice", Guid.NewGuid(), "user", IsActivated: isActivated, IsBlocked: false, MaxConfigs: 3,
+            MaxIpLimit: RoleQuota.Unlimited, SubscriptionToken: "sub-token");
+
+    [Fact]
+    public async Task Handle_WhenActivated_CallsNext()
+    {
+        var userId = Guid.NewGuid();
+        _currentUser.UserId.Returns(userId);
+        _identityService.GetProfileAsync(userId, Arg.Any<CancellationToken>()).Returns(CreateProfile(userId, isActivated: true));
+
+        var result = await CreateBehavior().Handle(
+            new DummyRequest(), () => Task.FromResult(Result.Success("ok")), CancellationToken.None);
+
+        Assert.True(result.IsSuccess);
+        Assert.Equal("ok", result.Value);
+    }
+
+    [Fact]
+    public async Task Handle_WhenNotActivated_ReturnsNotActivatedWithoutCallingNext()
+    {
+        var userId = Guid.NewGuid();
+        _currentUser.UserId.Returns(userId);
+        _identityService.GetProfileAsync(userId, Arg.Any<CancellationToken>()).Returns(CreateProfile(userId, isActivated: false));
+        var nextCalled = false;
+
+        var result = await CreateBehavior().Handle(
+            new DummyRequest(),
+            () =>
+            {
+                nextCalled = true;
+                return Task.FromResult(Result.Success("ok"));
+            },
+            CancellationToken.None);
+
+        Assert.False(result.IsSuccess);
+        Assert.Equal(AuthErrors.NotActivated, result.Error);
+        Assert.False(nextCalled);
+    }
+
+    [Fact]
+    public async Task Handle_WhenNoCurrentUser_ReturnsUnauthorized()
+    {
+        _currentUser.UserId.Returns((Guid?)null);
+
+        var result = await CreateBehavior().Handle(
+            new DummyRequest(), () => Task.FromResult(Result.Success("ok")), CancellationToken.None);
+
+        Assert.False(result.IsSuccess);
+        Assert.Equal(AuthErrors.Unauthorized, result.Error);
+    }
+
+    [Fact]
+    public async Task Handle_WhenProfileMissing_ReturnsUnauthorized()
+    {
+        var userId = Guid.NewGuid();
+        _currentUser.UserId.Returns(userId);
+        _identityService.GetProfileAsync(userId, Arg.Any<CancellationToken>()).Returns((CurrentUserProfile?)null);
+
+        var result = await CreateBehavior().Handle(
+            new DummyRequest(), () => Task.FromResult(Result.Success("ok")), CancellationToken.None);
+
+        Assert.False(result.IsSuccess);
+        Assert.Equal(AuthErrors.Unauthorized, result.Error);
+    }
+}