/**
 * Counts the real documents stored directly in a collection folder.
 *
 * Documents are flat `.axiodb` files in the collection root. Everything else
 * that lives there - the `indexes/` folder, `.transactions/` WAL staging, meta
 * files - is internal bookkeeping and must not be counted, which is why this is
 * neither recursive nor extension-agnostic.
 *
 * @param folderPath - Absolute path to the collection folder.
 * @returns Number of documents in that collection.
 */
export default function countDocumentsInFolder(folderPath: string): Promise<number>;