[Quality] Repo-wide audit fixes: error containment, drifted forks, silent failures (stacked on #294→#295) - #356

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@11d5960a326750d5838078e36cf38b85af677262, github/codeql-action/analyze@a2983b8bed1923f44751c5c43237f479442827b3, github/codeql-action/init@a2983b8bed1923f44751c5c43237f479442827b3. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/