Bundle brainstorm server dependencies instead of requiring npm install

Vendor node_modules into the repo so the brainstorm server works
immediately on fresh plugin installs without needing npm at runtime.

skills/brainstorming/scripts/node_modules/math-intrinsics/isNaN.js

@@ -0,0 +1,6 @@
+'use strict';
+
+/** @type {import('./isNaN')} */
+module.exports = Number.isNaN || function isNaN(a) {
+	return a !== a;
+};