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/lodash/_overArg.js

@@ -0,0 +1,15 @@
+/**
+ * Creates a unary function that invokes `func` with its argument transformed.
+ *
+ * @private
+ * @param {Function} func The function to wrap.
+ * @param {Function} transform The argument transform.
+ * @returns {Function} Returns the new function.
+ */
+function overArg(func, transform) {
+  return function(arg) {
+    return func(transform(arg));
+  };
+}
+
+module.exports = overArg;