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/findWhere.js

@@ -0,0 +1,10 @@
+var matcher = require('./matcher.js');
+var find = require('./find.js');
+
+// Convenience version of a common use case of `_.find`: getting the first
+// object containing specific `key:value` pairs.
+function findWhere(obj, attrs) {
+  return find(obj, matcher(attrs));
+}
+
+module.exports = findWhere;