refactor: improve code formatting and organization across multiple files

backend/app/db/session.py

@@ -9,16 +9,20 @@ from backend.app.core.config import get_settings
 
 settings = get_settings()
 
-engine = create_engine(settings.sqlalchemy_database_url, echo=settings.database_echo, future=True)
-SessionLocal = sessionmaker(bind=engine, autoflush=False, autocommit=False, expire_on_commit=False)
+engine = create_engine(
+    settings.sqlalchemy_database_url, echo=settings.database_echo, future=True
+)
+SessionLocal = sessionmaker(
+    bind=engine, autoflush=False, autocommit=False, expire_on_commit=False
+)
 
 
 def get_db_session() -> Generator[Session, None, None]:
-	session = SessionLocal()
-	try:
-		yield session
-	finally:
-		session.close()
+    session = SessionLocal()
+    try:
+        yield session
+    finally:
+        session.close()
 
 
 __all__ = ["engine", "SessionLocal", "get_db_session"]