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/core-js/modules/es.array.to-reversed.js

@@ -0,0 +1,17 @@
+'use strict';
+var $ = require('../internals/export');
+var arrayToReversed = require('../internals/array-to-reversed');
+var toIndexedObject = require('../internals/to-indexed-object');
+var addToUnscopables = require('../internals/add-to-unscopables');
+
+var $Array = Array;
+
+// `Array.prototype.toReversed` method
+// https://tc39.es/ecma262/#sec-array.prototype.toreversed
+$({ target: 'Array', proto: true }, {
+  toReversed: function toReversed() {
+    return arrayToReversed(toIndexedObject(this), $Array);
+  }
+});
+
+addToUnscopables('toReversed');