install.sh: no-Docker one-liner for cloud VPS
- Installs Node.js 20 via NodeSource if missing (Ubuntu/Debian/RHEL/Rocky)
- Clones to /opt/capsule, builds, creates a systemd service
- Re-running upgrades in place (git pull + rebuild)
Backup & Restore (Settings → Backup & Restore tab):
- Download Backup: streams all data/ as a .tar.gz (pure Node zlib, no deps)
- Restore: upload a .tar.gz to replace server data, auto sign-out after
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
