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/_listCacheGet.js

@@ -0,0 +1,19 @@
+var assocIndexOf = require('./_assocIndexOf');
+
+/**
+ * Gets the list cache value for `key`.
+ *
+ * @private
+ * @name get
+ * @memberOf ListCache
+ * @param {string} key The key of the value to get.
+ * @returns {*} Returns the entry value.
+ */
+function listCacheGet(key) {
+  var data = this.__data__,
+      index = assocIndexOf(data, key);
+
+  return index < 0 ? undefined : data[index][1];
+}
+
+module.exports = listCacheGet;