// iterating over the entire map, so a MapFS should typically be used with not more
// than a few hundred entries or directory reads.
type MapFS map[string]*MapFile

// A MapFile describes a single file in a [MapFS].
type MapFile struct {
	Data    []byte      // file content
	Mode    fs.FileMode // fs.FileInfo.Mode
	ModTime time.Time   // fs.FileInfo.ModTime
	Sys     any         // fs.FileInfo.Sys
}