When cluster IPC validation fails (due to systemd hardening), the proxy
falls back to allowlist-based validation. The installer now automatically
populates allowed_nodes with:
- Cluster mode: All discovered cluster member IPs
- Standalone mode: localhost IP addresses (including 127.0.0.1/localhost)
- Fallback mode: localhost IPs when pvecm unavailable
This ensures out-of-the-box temperature monitoring works on fresh installs
without manual configuration.
aba0eabd21