Initial commit: Developer Tools MVP with visual editor

- Complete React app with 7 developer tools
- JSON Tool with visual structured editor
- Serialize Tool with visual structured editor
- URL, Base64, CSV/JSON, Beautifier, Diff tools
- Responsive navigation with dropdown menu
- Dark/light mode toggle
- Mobile-responsive design with sticky header
- All tools working with copy/paste functionality

node_modules/has-proto/index.js

@@ -0,0 +1,15 @@
+'use strict';
+
+var test = {
+	__proto__: null,
+	foo: {}
+};
+
+// @ts-expect-error: TS errors on an inherited property for some reason
+var result = { __proto__: test }.foo === test.foo
+	&& !(test instanceof Object);
+
+/** @type {import('.')} */
+module.exports = function hasProto() {
+	return result;
+};