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/BigInt/sameValueZero.js

@@ -0,0 +1,15 @@
+'use strict';
+
+var $TypeError = require('es-errors/type');
+
+var BigIntEqual = require('./equal');
+
+// https://262.ecma-international.org/11.0/#sec-numeric-types-bigint-sameValueZero
+
+module.exports = function BigIntSameValueZero(x, y) {
+	if (typeof x !== 'bigint' || typeof y !== 'bigint') {
+		throw new $TypeError('Assertion failed: `x` and `y` arguments must be BigInts');
+	}
+
+	return BigIntEqual(x, y);
+};