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/workbox-webpack-plugin/build/index.d.ts

@@ -0,0 +1,11 @@
+import { GenerateSW, GenerateSWConfig } from './generate-sw';
+import { InjectManifest } from './inject-manifest';
+/**
+ * @module workbox-webpack-plugin
+ */
+export { GenerateSW, GenerateSWConfig, InjectManifest };
+declare const _default: {
+    GenerateSW: typeof GenerateSW;
+    InjectManifest: typeof InjectManifest;
+};
+export default _default;