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/cjs/random.js

@@ -0,0 +1,10 @@
+// Return a random integer between `min` and `max` (inclusive).
+function random(min, max) {
+  if (max == null) {
+    max = min;
+    min = 0;
+  }
+  return min + Math.floor(Math.random() * (max - min + 1));
+}
+
+module.exports = random;