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/every.js

@@ -0,0 +1,15 @@
+import cb from './_cb.js';
+import isArrayLike from './_isArrayLike.js';
+import keys from './keys.js';
+
+// Determine whether all of the elements pass a truth test.
+export default function every(obj, predicate, context) {
+  predicate = cb(predicate, context);
+  var _keys = !isArrayLike(obj) && keys(obj),
+      length = (_keys || obj).length;
+  for (var index = 0; index < length; index++) {
+    var currentKey = _keys ? _keys[index] : index;
+    if (!predicate(obj[currentKey], currentKey, obj)) return false;
+  }
+  return true;
+}