Enhance Telegram notification system with optional link support

- Updated NotifyUserAsync method in TelegramNotifier to accept an optional linkPath parameter for dynamic URL generation.
- Modified various command handlers to utilize the new linkPath feature, providing users with relevant links in their notifications.
- Adjusted ITelegramNotifier interface documentation to reflect the changes in method signature and functionality.
- Enhanced unit tests to verify the correct invocation of the updated NotifyUserAsync method.

backend/src/PnvPanel.Application/Admin/Users/BlockUserCommandHandler.cs

@@ -91,6 +91,7 @@ public sealed class BlockUserCommandHandler(
         await telegramNotifier.NotifyUserAsync(
             command.UserId,
             "⛔ Ваш аккаунт заблокирован администратором.",
+            null,
             cancellationToken
         );