/**
 * Generates a cryptographically random 256-bit nonce for the UGD
 * AuthorizedExecutions bitmap.
 *
 * Uses `crypto.getRandomValues` for 256 bits of entropy. Collisions against
 * the on-chain bitmap are effectively impossible at this width but callers
 * may still validate via `isNonceUsed` as a safety net.
 *
 * @returns A random bigint nonce.
 */
export declare const generateRandomNonce: () => bigint;