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/datalayout.js

@@ -1,7 +1,7 @@
 'use strict';
 
-const assert = require('assert'),
-    path = require('path');
+const assert = require('node:assert'),
+    path = require('node:path');
 
 class DataLayout {
     constructor(localRoot, dirMap) {