/**
 * Return the earliest (minimum) of the given PlainTime values.
 *
 * - Returns null if the array is empty or contains no valid times.
 * - Validation is performed on each item in the array.
 *
 * @param times Array of ISO PlainTime strings (e.g. "14:30:00")
 * @returns The earliest time string, or null on invalid input
 *
 * @example minTime(["14:30:00", "09:00:00", "20:45:00"]) // "09:00:00"
 * @example minTime([]) // null
 */
export declare function minTime(times: string[]): string | null;