refactor(backend): solve copilot comments

backend/alembic/README

@@ -1 +0,0 @@
-Generic single-database configuration.

backend/alembic/env.py

@@ -4,7 +4,7 @@ from logging.config import fileConfig
 from sqlalchemy import pool, create_engine
 from alembic import context
 
-# Přidání backend do sys.path pro správný import
+# Add path for correct loading of modules
 sys.path.insert(0, os.path.abspath(os.path.join(os.path.dirname(__file__), '..')))
 from app.core.db import Base
 
@@ -16,7 +16,6 @@ target_metadata = Base.metadata
 
 DATABASE_URL = os.getenv("DATABASE_URL")
 if not DATABASE_URL:
-    # fallback na synchronní url pro Alembic (používá sync driver)
     mariadb_host = os.getenv("MARIADB_HOST", "localhost")
     mariadb_port = os.getenv("MARIADB_PORT", "3306")
     mariadb_db = os.getenv("MARIADB_DB", "group_project")
@@ -24,7 +23,7 @@ if not DATABASE_URL:
     mariadb_password = os.getenv("MARIADB_PASSWORD", "strongpassword")
     DATABASE_URL = f"mysql+pymysql://{mariadb_user}:{mariadb_password}@{mariadb_host}:{mariadb_port}/{mariadb_db}"
 
-# Vždy používej synchronní engine pro migrace
+# Use synchronous driver for Alembic migrations
 SYNC_DATABASE_URL = DATABASE_URL.replace("+asyncmy", "+pymysql")