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-background-sync/BackgroundSyncPlugin.d.ts

@@ -0,0 +1,27 @@
+import { WorkboxPlugin } from 'workbox-core/types.js';
+import { QueueOptions } from './Queue.js';
+import './_version.js';
+/**
+ * A class implementing the `fetchDidFail` lifecycle callback. This makes it
+ * easier to add failed requests to a background sync Queue.
+ *
+ * @memberof workbox-background-sync
+ */
+declare class BackgroundSyncPlugin implements WorkboxPlugin {
+    private readonly _queue;
+    /**
+     * @param {string} name See the {@link workbox-background-sync.Queue}
+     *     documentation for parameter details.
+     * @param {Object} [options] See the
+     *     {@link workbox-background-sync.Queue} documentation for
+     *     parameter details.
+     */
+    constructor(name: string, options?: QueueOptions);
+    /**
+     * @param {Object} options
+     * @param {Request} options.request
+     * @private
+     */
+    fetchDidFail: WorkboxPlugin['fetchDidFail'];
+}
+export { BackgroundSyncPlugin };