refactoring: polished some files, .env.example update

bot/keyboards/client.py

@@ -4,6 +4,7 @@ from aiogram.utils.keyboard import InlineKeyboardBuilder
 from config import settings
 from misc.utils import convert_duration_to_int
 from schemas.subscriptions import SubscriptionDuration
+
 from .common import _return_to_menu_btn
 
 main_menu = InlineKeyboardBuilder(