[Chore] 훈장 설명과 미션 제목을 서버에 맞춰 숫자로 바꾼다 - #278

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@v4. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/