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/map.js

@@ -0,0 +1,18 @@
+var keys = require('./keys.js');
+var _cb = require('./_cb.js');
+var _isArrayLike = require('./_isArrayLike.js');
+
+// Return the results of applying the iteratee to each element.
+function map(obj, iteratee, context) {
+  iteratee = _cb(iteratee, context);
+  var _keys = !_isArrayLike(obj) && keys(obj),
+      length = (_keys || obj).length,
+      results = Array(length);
+  for (var index = 0; index < length; index++) {
+    var currentKey = _keys ? _keys[index] : index;
+    results[index] = iteratee(obj[currentKey], currentKey, obj);
+  }
+  return results;
+}
+
+module.exports = map;