Refactor code structure for improved readability and maintainability

client/node_modules/postcss/lib/stringify.d.ts

@@ -0,0 +1,9 @@
+import { Stringifier } from './postcss.js'
+
+interface Stringify extends Stringifier {
+  default: Stringify
+}
+
+declare const stringify: Stringify
+
+export = stringify