The setup script now adds both the restricted and unrestricted SSH keys
to ALL cluster nodes, not just the first one. This makes temperature
monitoring truly turnkey - you say 'yes' to configure cluster nodes and
it automatically sets up both keys on each node.
This ensures:
- All nodes can act as ProxyJump hosts if needed
- All nodes can provide temperature data via sensors
- No manual SSH key configuration required
Fixes turnkey cluster temperature monitoring setup.