Function ensure_signing_key
pub fn ensure_signing_key(data_dir: &Path) -> Result<Vec<u8>>Expand description
Load (or create + persist) the daemon’s Ed25519 relay-registration key.
Stored as raw PKCS#8 DER at <data_dir>/relay/registration.key (dir 0700,
key 0600). This is the daemon’s stable rendezvous identity, separate from the
ZeroClaw CA: the relay binds the node-id to this key and an allowlist keys on
its fingerprint.