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/mz/index.js

@@ -0,0 +1,8 @@
+module.exports = {
+  fs: require('./fs'),
+  dns: require('./dns'),
+  zlib: require('./zlib'),
+  crypto: require('./crypto'),
+  readline: require('./readline'),
+  child_process: require('./child_process')
+}