[ryoku] launcher: fix race condition causing empty app list at startup - #752

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/

origin/main is 122 commit(s) behind origin/unstable-dev; users get them only after main fast-forwards and publish-repo runs.