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-core/clientsClaim.js

@@ -0,0 +1,18 @@
+/*
+  Copyright 2019 Google LLC
+
+  Use of this source code is governed by an MIT-style
+  license that can be found in the LICENSE file or at
+  https://opensource.org/licenses/MIT.
+*/
+import './_version.js';
+/**
+ * Claim any currently available clients once the service worker
+ * becomes active. This is normally used in conjunction with `skipWaiting()`.
+ *
+ * @memberof workbox-core
+ */
+function clientsClaim() {
+    self.addEventListener('activate', () => self.clients.claim());
+}
+export { clientsClaim };