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/modules/bind.js

@@ -0,0 +1,13 @@
+import restArguments from './restArguments.js';
+import isFunction from './isFunction.js';
+import executeBound from './_executeBound.js';
+
+// Create a function bound to a given object (assigning `this`, and arguments,
+// optionally).
+export default restArguments(function(func, context, args) {
+  if (!isFunction(func)) throw new TypeError('Bind must be called on a function');
+  var bound = restArguments(function(callArgs) {
+    return executeBound(func, bound, context, this, args.concat(callArgs));
+  });
+  return bound;
+});