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.reflect.delete-property.js

@@ -0,0 +1,13 @@
+'use strict';
+var $ = require('../internals/export');
+var anObject = require('../internals/an-object');
+var getOwnPropertyDescriptor = require('../internals/object-get-own-property-descriptor').f;
+
+// `Reflect.deleteProperty` method
+// https://tc39.es/ecma262/#sec-reflect.deleteproperty
+$({ target: 'Reflect', stat: true }, {
+  deleteProperty: function deleteProperty(target, propertyKey) {
+    var descriptor = getOwnPropertyDescriptor(anObject(target), propertyKey);
+    return descriptor && !descriptor.configurable ? false : delete target[propertyKey];
+  }
+});