/**
 * Converts a MIME type to a file extension.
 * @param mimeType - The MIME type string (may include charset and other parameters)
 * @returns The file extension with leading dot (e.g., '.html'), or empty string if unknown
 * @example
 * ```ts
 * mimeToExtension('text/html; charset=utf-8') // '.html'
 * mimeToExtension('application/javascript') // '.js'
 * mimeToExtension('unknown/type') // ''
 * ```
 */
export declare function mimeToExtension(mimeType?: string): string;