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/mailserver.js

@@ -22,23 +22,23 @@ exports = module.exports = {
     DEFAULT_MEMORY_LIMIT: 512 * 1024 * 1024,
 };
 
-const assert = require('assert'),
+const assert = require('node:assert'),
     BoxError = require('./boxerror.js'),
     constants = require('./constants.js'),
-    crypto = require('crypto'),
+    crypto = require('node:crypto'),
     debug = require('debug')('box:mailserver'),
     dns = require('./dns.js'),
     docker = require('./docker.js'),
     domains = require('./domains.js'),
     eventlog = require('./eventlog.js'),
-    fs = require('fs'),
+    fs = require('node:fs'),
     hat = require('./hat.js'),
     infra = require('./infra_version.js'),
     Location = require('./location.js'),
     locks = require('./locks.js'),
     mail = require('./mail.js'),
-    os = require('os'),
-    path = require('path'),
+    os = require('node:os'),
+    path = require('node:path'),
     paths = require('./paths.js'),
     platform = require('./platform.js'),
     reverseProxy = require('./reverseproxy.js'),