/**
 * Finds an available port for listening.
 *
 * @param startingAt - Port to begin scanning from (default: 3000).
 * @returns A Promise that resolves to an unused port number.
 * @throws If no available port is found in the range 3000-65535.
 * @example
 * const port = await getAvailablePort(8080);
 * console.log(`${port} is available`);
 */
export declare function getAvailablePort(startingAt?: number): Promise<number>;