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/CreateLinkTokenCommandHandler.cs

@@ -0,0 +1,24 @@
+using PnvPanel.Application.Auth;
+using PnvPanel.Application.Common.Interfaces;
+using PnvPanel.Application.Common.Messaging;
+using PnvPanel.Application.Common.Models;
+using PnvPanel.Domain.Telegram;
+
+namespace PnvPanel.Application.Telegram;
+
+public sealed class CreateLinkTokenCommandHandler(IAppDbContext dbContext, ICurrentUser currentUser)
+    : ICommandHandler<CreateLinkTokenCommand, Result<LinkTokenDto>>
+{
+    private static readonly TimeSpan Ttl = TimeSpan.FromMinutes(5);
+
+    public Task<Result<LinkTokenDto>> Handle(CreateLinkTokenCommand command, CancellationToken cancellationToken)
+    {
+        if (currentUser.UserId is not { } userId)
+            return Task.FromResult(Result.Failure<LinkTokenDto>(AuthErrors.Unauthorized));
+
+        var token = TelegramLinkToken.Create(userId, Ttl);
+        dbContext.TelegramLinkTokens.Add(token);
+
+        return Task.FromResult(Result.Success(new LinkTokenDto(token.Token, token.ExpiresAt)));
+    }
+}