signLicenseChallenge() function
Sign an engine license-challenge nonce with an identity’s Ed25519 private key (PKCS#8 PEM). Exposed for runtimes that assemble a richer challenge response (e.g. relaying a signed workflow); most callers want createLicenseChallengeResponder().
Signature:
export declare function signLicenseChallenge(keyPem: string, challenge: Uint8Array): Uint8Array;