refactor(backend): solve copilot comments

backend/app/core/db.py

@@ -1,6 +1,6 @@
 import os
 from sqlalchemy.ext.asyncio import create_async_engine, async_sessionmaker
-from app.core.base import Base  # Import Base z nového souboru
+from app.core.base import Base
 
 DATABASE_URL = os.getenv("DATABASE_URL")
 if not DATABASE_URL:
@@ -14,15 +14,11 @@ if not DATABASE_URL:
     else:
         raise Exception("Only MariaDB is supported. Please set the DATABASE_URL environment variable.")
 
-# Explicitní import všech modelů, aby byly registrovány v Base.metadata
+# Load all models to register them
+
 from app.models.user import User
 from app.models.transaction import Transaction
 
-from app.models.user import User
-
-# Pokud máš další modely, importuj je zde:
-# from app.models.other_model import OtherModel
-
 ssl_enabled = os.getenv("MARIADB_HOST", "localhost") != "localhost"
 connect_args = {"ssl": {"ssl": True}} if ssl_enabled else {}