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/underscore/modules/create.js

@@ -0,0 +1,11 @@
+import baseCreate from './_baseCreate.js';
+import extendOwn from './extendOwn.js';
+
+// Creates an object that inherits from the given prototype object.
+// If additional properties are provided then they will be added to the
+// created object.
+export default function create(prototype, props) {
+  var result = baseCreate(prototype);
+  if (props) extendOwn(result, props);
+  return result;
+}