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/head.js

@@ -0,0 +1,23 @@
+/**
+ * Gets the first element of `array`.
+ *
+ * @static
+ * @memberOf _
+ * @since 0.1.0
+ * @alias first
+ * @category Array
+ * @param {Array} array The array to query.
+ * @returns {*} Returns the first element of `array`.
+ * @example
+ *
+ * _.head([1, 2, 3]);
+ * // => 1
+ *
+ * _.head([]);
+ * // => undefined
+ */
+function head(array) {
+  return (array && array.length) ? array[0] : undefined;
+}
+
+module.exports = head;