feat: 회원 탈퇴를 공급자 인가 왕복 흐름에 맞춘다 - #97

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683, actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02, docker/build-push-action@263435318d21b8e681c14492fe198d362a7d2c83, docker/setup-buildx-action@e468171a9de216ec08956ac3ada2f0791b6bd435. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/