/**
 * Resize and square-crop an image file for use as an avatar.
 *
 * The image is center-cropped to a square, scaled down to at most {@link size} pixels,
 * and converted to the specified output format.
 *
 * @param file - The source image file.
 * @param size - Max dimension in pixels for the output image.
 * @param extension - Output format. Use `"inherit"` to keep the original format.
 * @returns A promise that resolves to the processed `File`.
 */
export declare function resizeAvatar(file: File, size?: number, extension?: "png" | "jpg" | "webp" | "inherit"): Promise<File>;
/**
 * Convert a `File` to a base64-encoded data URL string.
 *
 * @param file - The file to encode.
 * @returns A promise that resolves to the base64 data URL.
 */
export declare function fileToBase64(file: File): Promise<string>;