fix: resolve database connection issue in docker environment

docker-compose.yml

@@ -13,5 +13,7 @@ services:
     # 환경 변수 설정
     environment:
       - PYTHONUNBUFFERED=1
+      - DB_HOST=aicode-db
+      - DB_PORT=3306
     # 컨테이너 종료 시 자동 재시작
     restart: always