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/backups.js

@@ -25,7 +25,7 @@ exports = module.exports = {
     BACKUP_STATE_ERROR: 'error',
 };
 
-const assert = require('assert'),
+const assert = require('node:assert'),
     BoxError = require('./boxerror.js'),
     database = require('./database.js'),
     hat = require('./hat.js'),