Embed the shipped data, load any fs.FS, New takes options, Fake is safe for concurrent use

render.go

@@ -18,6 +18,8 @@ type rng interface {
 // e.g. "sv_SE.address" or "sv_SE.address.street". Choices along the way are
 // resolved at random. A path naming a folder (no value of its own) is an error.
 func (f *Generator) Fake(path string) (string, error) {
+	f.mu.Lock()
+	defer f.mu.Unlock()
 	n, err := descend(f.rand, &group{children: f.categories}, strings.Split(path, "."))
 	if err != nil {
 		return "", fmt.Errorf("fejkdata: %s: %w", path, err)