absolute path of the picked folder (in the fs plugin's runtime scope).
getDirectoryHandle(create) — create a directory.
getFile().text()/arrayBuffer() — read a file (base64 when binary).
removeEntry — delete a file or directory.
createWritable().write — write a file (data is base64 when binary).
FsResponder over a user-picked absolute directory, via the Tauri fs plugin.