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/htmlparser2/lib/CollectingHandler.d.ts

@@ -0,0 +1,10 @@
+import MultiplexHandler from "./MultiplexHandler";
+import { Handler } from "./Parser";
+export declare class CollectingHandler extends MultiplexHandler {
+    private readonly cbs;
+    events: [keyof Handler, ...unknown[]][];
+    constructor(cbs?: Partial<Handler>);
+    onreset(): void;
+    restart(): void;
+}
+//# sourceMappingURL=CollectingHandler.d.ts.map