We can create them and see them on the file dialogs, but not yet load
them back.
I want stashed files to remember the original filename. I think that
implies the ability to add a note to them. But I don't yet know how to
represent the note on disk.
And this creates cascading questions, like should editing a stash file
continue to modify it or create a new version? How to create a new
version? Should unstash copy or move?