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/function-uncurry-this-accessor.js

@@ -0,0 +1,10 @@
+'use strict';
+var uncurryThis = require('../internals/function-uncurry-this');
+var aCallable = require('../internals/a-callable');
+
+module.exports = function (object, key, method) {
+  try {
+    // eslint-disable-next-line es/no-object-getownpropertydescriptor -- safe
+    return uncurryThis(aCallable(Object.getOwnPropertyDescriptor(object, key)[method]));
+  } catch (error) { /* empty */ }
+};