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/jest-pnp-resolver/getDefaultResolver.js

@@ -0,0 +1,13 @@
+let defaultResolver;
+
+module.exports = () => {
+  if (!defaultResolver) {
+    try {
+      defaultResolver = require(`jest-resolve/build/defaultResolver`).default;
+    } catch (error) {
+      defaultResolver = require(`jest-resolve/build/default_resolver`).default;
+    }
+  }
+
+  return defaultResolver;
+};