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/reusify/benchmarks/fib.js

@@ -0,0 +1,13 @@
+'use strict'
+
+function fib (num) {
+  var fib = []
+
+  fib[0] = 0
+  fib[1] = 1
+  for (var i = 2; i <= num; i++) {
+    fib[i] = fib[i - 2] + fib[i - 1]
+  }
+}
+
+module.exports = fib