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/internals/get-iterator-flattenable.js

@@ -0,0 +1,11 @@
+'use strict';
+var call = require('../internals/function-call');
+var anObject = require('../internals/an-object');
+var getIteratorDirect = require('../internals/get-iterator-direct');
+var getIteratorMethod = require('../internals/get-iterator-method');
+
+module.exports = function (obj, stringHandling) {
+  if (!stringHandling || typeof obj !== 'string') anObject(obj);
+  var method = getIteratorMethod(obj);
+  return getIteratorDirect(anObject(method !== undefined ? call(method, obj) : obj));
+};