feat: implement billing system with Pally integration

- Added billing models and repository for handling bills.
- Introduced BillingService to manage payment initiation and bill creation.
- Updated user service to remove ticket-related functionality.
- Refactored settings to include new billing-related fields.
- Removed ticket-related handlers and schemas.
- Added new billing handlers for processing payments.
- Updated database schema with new bills table and status enum.
- Enhanced utility functions to calculate prices considering discounts.
- Introduced prehandling for non-private messages.
- Updated main application to initialize new billing services and repositories.

handlers/prehandling.py

@@ -0,0 +1,9 @@
+from aiogram import F, Router
+from aiogram.types import Message
+
+router = Router()
+
+
+@router.message(F.chat.type != "private")
+async def prehandle_non_private(msg: Message):
+    return