Refactor configuration and enhance Telegram initData validation

- Improved formatting and readability in config.py and other files by adding line breaks.
- Introduced INIT_DATA_MAX_AGE_SECONDS to enforce replay protection for Telegram initData.
- Updated validate_init_data function to include max_age_seconds parameter for validation.
- Enhanced API to reject old initData based on the new max_age_seconds setting.
- Added tests for auth_date expiry and validation of initData in test_telegram_auth.py.
- Updated README with details on the new INIT_DATA_MAX_AGE_SECONDS configuration.

db/session.py

@@ -1,11 +1,11 @@
 """SQLAlchemy engine and session factory."""
+
 from contextlib import contextmanager
 from typing import Generator
 
 from sqlalchemy import create_engine
 from sqlalchemy.orm import Session, sessionmaker
 
-from db.models import Base
 
 _engine = None
 _SessionLocal = None
@@ -26,7 +26,9 @@ def get_engine(database_url: str):
     if _engine is None:
         _engine = create_engine(
             database_url,
-            connect_args={"check_same_thread": False} if "sqlite" in database_url else {},
+            connect_args={"check_same_thread": False}
+            if "sqlite" in database_url
+            else {},
             echo=False,
         )
     return _engine