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-pure/modules/es.number.parse-int.js

@@ -0,0 +1,10 @@
+'use strict';
+var $ = require('../internals/export');
+var parseInt = require('../internals/number-parse-int');
+
+// `Number.parseInt` method
+// https://tc39.es/ecma262/#sec-number.parseint
+// eslint-disable-next-line es/no-number-parseint -- required for testing
+$({ target: 'Number', stat: true, forced: Number.parseInt !== parseInt }, {
+  parseInt: parseInt
+});