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/ipaddr.js

@@ -7,8 +7,8 @@ exports = module.exports = {
     includes,
 };
 
-const assert = require('assert'),
-    net = require('net');
+const assert = require('node:assert'),
+    net = require('node:net');
 
 function isValid(ip) {
     assert.strictEqual(typeof ip, 'string');