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/2025/Number/sameValue.js

@@ -0,0 +1,18 @@
+'use strict';
+
+var isNegativeZero = require('math-intrinsics/isNegativeZero');
+var $TypeError = require('es-errors/type');
+
+var NumberSameValueZero = require('./sameValueZero');
+
+// https://262.ecma-international.org/11.0/#sec-numeric-types-number-sameValue
+
+module.exports = function NumberSameValue(x, y) {
+	if (typeof x !== 'number' || typeof y !== 'number') {
+		throw new $TypeError('Assertion failed: `x` and `y` arguments must be Numbers');
+	}
+	if (x === 0 && y === 0) {
+		return !(isNegativeZero(x) ^ isNegativeZero(y));
+	}
+	return NumberSameValueZero(x, y);
+};