/**
 * Format a date using Intl.DateTimeFormat
 * @param date - Date to format
 * @param options - Intl.DateTimeFormat options
 * @param locale - Locale string (defaults to 'en-US')
 * @returns Formatted date string
 */
export declare function formatDate(date: Date, options?: Intl.DateTimeFormatOptions, locale?: string): string;