/**
 * Return the hour (0-23) from a UTC datetime string.
 *
 * - Returns zero-padded string for hour.
 * - Returns "" for invalid input.
 *
 * @param value ISO UTC datetime string (e.g., "2024-03-17T14:30:45Z")
 * @returns Hour (00-23) or "" on invalid input
 *
 * @example parseHourFromUtc("2024-03-17T14:30:45Z") // "14"
 * @example parseHourFromUtc("invalid") // ""
 */
export declare function parseHourFromUtc(value: string): string;