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/test/shell-test.js

@@ -6,7 +6,7 @@
 
 const BoxError = require('../boxerror.js'),
     expect = require('expect.js'),
-    path = require('path'),
+    path = require('node:path'),
     safe = require('safetydance'),
     shell = require('../shell.js')('test');