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.string.code-point-at.js

@@ -0,0 +1,11 @@
+'use strict';
+var $ = require('../internals/export');
+var codeAt = require('../internals/string-multibyte').codeAt;
+
+// `String.prototype.codePointAt` method
+// https://tc39.es/ecma262/#sec-string.prototype.codepointat
+$({ target: 'String', proto: true }, {
+  codePointAt: function codePointAt(pos) {
+    return codeAt(this, pos);
+  }
+});