use node: prefix for requires

mostly because code is being autogenerated by all the AI stuff using
this prefix. it's also used in the stack trace.

src/constants.js

@@ -1,7 +1,7 @@
 'use strict';
 
-const fs = require('fs'),
-    path = require('path');
+const fs = require('node:fs'),
+    path = require('node:path');
 
 const CLOUDRON = process.env.BOX_ENV === 'cloudron',
     TEST = process.env.BOX_ENV === 'test';