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/taskworker.js

@@ -11,10 +11,10 @@ const apptask = require('./apptask.js'),
     dns = require('./dns.js'),
     dyndns = require('./dyndns.js'),
     externalLdap = require('./externalldap.js'),
-    fs = require('fs'),
+    fs = require('node:fs'),
     locks = require('./locks.js'),
     mailServer = require('./mailserver.js'),
-    net = require('net'),
+    net = require('node:net'),
     reverseProxy = require('./reverseproxy.js'),
     safe = require('safetydance'),
     tasks = require('./tasks.js'),