/**
 * Return true when `value1` is strictly before `value2` for PlainDateTime values.
 *
 * - Uses Temporal.PlainDateTime.compare to compare date-times.
 * - Returns false if either input is invalid.
 *
 * @param value1 ISO PlainDateTime string for the first value
 * @param value2 ISO PlainDateTime string for the second value
 * @returns boolean indicating whether value1 < value2
 *
 * @example isBeforeDateTime("2024-02-28T12:34:56", "2024-02-29T12:34:56") // true
 * @example isBeforeDateTime("2024-02-29T12:34:56", "2024-02-29T12:34:56") // false
 * @example isBeforeDateTime("2024-02-29T12:34:56", "2024-02-28T12:34:56") // false
 * @example isBeforeDateTime("invalid", "2024-02-29T12:34:56") // false
 * @example isBeforeDateTime("2024-02-29T12:34:56", "invalid") // false
 */
export declare function isBeforeDateTime(value1: string, value2: string): boolean;