/**
 * Return the hour (0-23) for a given ISO 8601 time string.
 *
 * - Returns zero-padded string for hour.
 * - Returns "" for invalid input.
 *
 * @param value ISO time string
 * @returns Hour (00-23) or "" on invalid input
 *
 * @example parseHourFromTime("12:30:00") // "12"
 * @example parseHourFromTime("invalid") // ""
 */
export declare function parseHourFromTime(value: string): string;