Nano node RPC bind address and control interface exposure

Nano node RPC interface exposure must be limited to intended network interfaces to avoid accidental public access to node and wallet operations.

The `config-node.toml` file controls the RPC listen address, port, and whether control is enabled. Binding to `0.0.0.0` exposes the interface on all interfaces, while `127.0.0.1` limits it to localhost. Many RPC endpoints historically lack built-in authentication, so the network binding is the primary access boundary.

It is unclear whether the shipped default binds RPC to localhost only or to all interfaces, and whether enabling control implicitly opens the port without authentication. Defaults may vary by Nano node version and installation method, such as package, source build, or container.

• What is the default RPC listen address for a Nano node installed from a package?
• Does setting `enable_control = true` open the RPC port without any authentication mechanism?
• Which configuration keys definitively restrict the interface to localhost before the node starts?