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.

schemas/di.py

@@ -2,14 +2,18 @@ from dataclasses import dataclass
 
 from remnawave import RemnawaveSDK
 
-from repositories.tickets import TicketRepository
+from misc.pally import PallyClient
+from repositories.bills import BillsRepository
 from repositories.users import UserRepository
+from services.billing_service import BillingService
 from services.user_service import UserService
 
 
 @dataclass
 class DependenciesDTO:
-    ticket_repository: TicketRepository
     user_repository: UserRepository
     user_service: UserService
     rw_sdk: RemnawaveSDK
+    bills_repository: BillsRepository
+    billing_service: BillingService
+    pally_client: PallyClient