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/src/PnvPanel.Application/Configs/Create/CreateVpnConfigCommand.cs

@@ -3,4 +3,4 @@ using PnvPanel.Application.Common.Models;
 
 namespace PnvPanel.Application.Configs.Create;
 
-public sealed record CreateVpnConfigCommand(Guid InboundId, string? Label) : ICommand<Result<VpnConfigDto>>;
+public sealed record CreateVpnConfigCommand(Guid InboundId, string? Label) : ICommand<Result<VpnConfigDto>>, IRequiresActivation;

backend/src/PnvPanel.Application/Configs/Create/CreateVpnConfigCommandHandler.cs

@@ -20,9 +20,6 @@ public sealed class CreateVpnConfigCommandHandler(
         if (profile is null)
             return Result.Failure<VpnConfigDto>(AuthErrors.Unauthorized);
 
-        if (!profile.IsActivated)
-            return Result.Failure<VpnConfigDto>(ConfigErrors.NotActivated);
-
         var inbound = await dbContext.Inbounds.AsNoTracking()
             .FirstOrDefaultAsync(i => i.Id == command.InboundId, cancellationToken);