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/@testing-library/user-event/dist/utils/edit/getValue.js

@@ -0,0 +1,21 @@
+"use strict";
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+exports.getValue = getValue;
+
+var _isContentEditable = require("./isContentEditable");
+
+function getValue(element) {
+  // istanbul ignore if
+  if (!element) {
+    return null;
+  }
+
+  if ((0, _isContentEditable.isContentEditable)(element)) {
+    return element.textContent;
+  }
+
+  return element.value;
+}