Add Telegram bot integration and enhance user management features

- Introduced Telegram.Bot package for bot functionality.
- Updated user management to include Telegram linking and blocking features.
- Enhanced activation request handling with notifications via Telegram.
- Added new database entities for Telegram link tokens and login requests.
- Implemented traffic synchronization for client stats in the XuiPanelGateway.
- Updated application structure to support new test projects and improved dependency injection for Telegram services.

backend/src/PnvPanel.Application/Telegram/CreateLoginRequestCommand.cs

@@ -0,0 +1,9 @@
+using PnvPanel.Application.Common.Messaging;
+using PnvPanel.Application.Common.Models;
+
+namespace PnvPanel.Application.Telegram;
+
+/// <summary>Публичная команда (пользователь ещё не залогинен) — начинает passwordless-вход.</summary>
+public sealed record CreateLoginRequestCommand(string? Context) : ICommand<Result<LoginRequestDto>>;
+
+public sealed record LoginRequestDto(Guid RequestId, DateTimeOffset ExpiresAt);