/**
 * Truncates a string to a given maximum length, respecting word boundaries if possible.
 *
 * @example
 * truncate("The quick brown fox jumps over the lazy dog", 20) // "The quick brown fox..."
 *
 * @param str The string to truncate.
 * @param maxLength The maximum allowed length including ellipsis.
 * @param ellipsis The truncation suffix (default: "...").
 * @returns The truncated string.
 */
export declare function truncate(str: string, maxLength: number, ellipsis?: string): string;