Enhance Telegram bot functionality and configuration options

- Added new inline button features to the `/configs` command, allowing users to view their configurations in a single message with active links and a back button.
- Implemented a menu for unlinking Telegram accounts, providing a clearer user experience when managing account connections.
- Updated the `.env.example` file to include a new `Telegram__PublicSiteUrl` setting, enabling a button for accessing the panel's website directly from the bot.
- Enhanced documentation to reflect the new features and configuration options available in the Telegram bot.

backend/src/PnvPanel.Infrastructure/Telegram/TelegramOptions.cs

@@ -5,6 +5,8 @@ public sealed class TelegramOptions
     public const string SectionName = "Telegram";
 
     public string? BotToken { get; init; }
+
+    /// <summary>Ссылка на сайт панели — кнопка «🌐 Сайт панели» в главном меню бота. Пусто — кнопки нет.</summary>
     public string PublicSiteUrl { get; init; } = string.Empty;
 
     /// <summary>Прокси для запросов к Bot API (обычно socks5://[user:pass@]host:port). Пусто — без прокси.</summary>