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/dom/dist/get-node-text.js

@@ -0,0 +1,13 @@
+"use strict";
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+exports.getNodeText = getNodeText;
+var _helpers = require("./helpers");
+function getNodeText(node) {
+  if (node.matches('input[type=submit], input[type=button], input[type=reset]')) {
+    return node.value;
+  }
+  return Array.from(node.childNodes).filter(child => child.nodeType === _helpers.TEXT_NODE && Boolean(child.textContent)).map(c => c.textContent).join('');
+}