/**
 * Generates a UUID v4 string. Uses `crypto.randomUUID` when available,
 * otherwise falls back to `crypto.getRandomValues`.
 *
 * @returns {string} A UUID v4 in canonical 8-4-4-4-12 hex form
 * @example
 * randomUUID(); // e.g. "1b9d6bcd-bbfd-4b2d-9b5d-ab8dfbbd4bed"
 */
export declare const randomUUID: () => string;