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/es-abstract/2020/ToPrimitive.js

@@ -0,0 +1,12 @@
+'use strict';
+
+var toPrimitive = require('es-to-primitive/es2015');
+
+// https://262.ecma-international.org/6.0/#sec-toprimitive
+
+module.exports = function ToPrimitive(input) {
+	if (arguments.length > 1) {
+		return toPrimitive(input, arguments[1]);
+	}
+	return toPrimitive(input);
+};