v4.0 fixes (auth, cache, snapshot, Proxmox, OAuth2 logout, TOTP, X2GO, PhysicalMachines) - #191

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@v3, actions/dependency-review-action@v3. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/