/**
 * Sort an array of PlainDate values in ascending or descending order.
 *
 * - Returns empty array if no valid dates.
 * - Validation is performed on each item in the array.
 *
 * @param dates Array of ISO PlainDate strings (e.g. "2024-03-10")
 * @param order "asc" for ascending (earliest first) | "desc" for descending (latest first)
 * @returns Sorted array of date strings
 *
 * @example sortDates(["2024-03-10", "2024-01-01", "2024-02-15"]) // ["2024-01-01", "2024-02-15", "2024-03-10"]
 * @example sortDates([]) // []
 */
export declare function sortDates(dates: string[], order?: "asc" | "desc"): string[];