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/react-app-polyfill/package.json

@@ -0,0 +1,32 @@
+{
+  "name": "react-app-polyfill",
+  "version": "3.0.0",
+  "description": "Polyfills for various browsers including commonly used language features",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/facebook/create-react-app.git",
+    "directory": "packages/react-app-polyfill"
+  },
+  "license": "MIT",
+  "bugs": {
+    "url": "https://github.com/facebook/create-react-app/issues"
+  },
+  "engines": {
+    "node": ">=14"
+  },
+  "files": [
+    "ie9.js",
+    "ie11.js",
+    "jsdom.js",
+    "stable.js"
+  ],
+  "dependencies": {
+    "core-js": "^3.19.2",
+    "object-assign": "^4.1.1",
+    "promise": "^8.1.0",
+    "raf": "^3.4.1",
+    "regenerator-runtime": "^0.13.9",
+    "whatwg-fetch": "^3.6.2"
+  },
+  "gitHead": "221e511730ca51c036c6954a9d2ee7659ff860f9"
+}