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/last.js

@@ -0,0 +1,11 @@
+var rest = require('./rest.js');
+
+// Get the last element of an array. Passing **n** will return the last N
+// values in the array.
+function last(array, n, guard) {
+  if (array == null || array.length < 1) return n == null || guard ? void 0 : [];
+  if (n == null || guard) return array[array.length - 1];
+  return rest(array, Math.max(0, array.length - n));
+}
+
+module.exports = last;