/**
 * Return true when the input is a valid PlainDate or PlainDateTime ISO string.
 *
 * - Accepts both PlainDate ("2024-02-29") and PlainDateTime ("2024-02-29T12:34:56") formats.
 * - Uses regex to check format before parsing.
 * - Rejects leap seconds and invalid dates/times.
 *
 * @param value ISO PlainDate or PlainDateTime string
 * @returns boolean indicating validity
 *
 * @example isValidIsoDateLike("2024-02-29") // true
 * @example isValidIsoDateLike("2024-02-30") // false (invalid date)
 * @example isValidIsoDateLike("2024-02-29T12:34:56") // true
 * @example isValidIsoDateLike("2024-02-29T24:00:00") // false (invalid time)
 * @example isValidIsoDateLike("2024-12-31T23:59:60") // false (leap second)
 */
export declare function isValidIsoDateLike(value: string): boolean;