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/async/internal/map.js

@@ -0,0 +1,30 @@
+'use strict';
+
+Object.defineProperty(exports, "__esModule", {
+    value: true
+});
+exports.default = _asyncMap;
+
+var _wrapAsync = require('./wrapAsync.js');
+
+var _wrapAsync2 = _interopRequireDefault(_wrapAsync);
+
+function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
+
+function _asyncMap(eachfn, arr, iteratee, callback) {
+    arr = arr || [];
+    var results = [];
+    var counter = 0;
+    var _iteratee = (0, _wrapAsync2.default)(iteratee);
+
+    return eachfn(arr, (value, _, iterCb) => {
+        var index = counter++;
+        _iteratee(value, (err, v) => {
+            results[index] = v;
+            iterCb(err);
+        });
+    }, err => {
+        callback(err, results);
+    });
+}
+module.exports = exports.default;