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/provision.js

@@ -8,7 +8,7 @@ exports = module.exports = {
 };
 
 const appstore = require('./appstore.js'),
-    assert = require('assert'),
+    assert = require('node:assert'),
     backupTargets = require('./backuptargets.js'),
     backups = require('./backups.js'),
     backuptask = require('./backuptask.js'),
@@ -19,7 +19,7 @@ const appstore = require('./appstore.js'),
     dns = require('./dns.js'),
     domains = require('./domains.js'),
     eventlog = require('./eventlog.js'),
-    fs = require('fs'),
+    fs = require('node:fs'),
     mail = require('./mail.js'),
     mailServer = require('./mailserver.js'),
     network = require('./network.js'),