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/fork-ts-checker-webpack-plugin/lib/rpc/RpcMessagePort.d.ts

@@ -0,0 +1,14 @@
+declare type RpcMessageDispatch = <TMessage>(message: TMessage) => Promise<void>;
+declare type RpcMessageListener = RpcMessageDispatch;
+declare type RpcErrorListener = (error: Error) => void;
+interface RpcMessagePort {
+    readonly dispatchMessage: RpcMessageDispatch;
+    readonly addMessageListener: (listener: RpcMessageListener) => void;
+    readonly removeMessageListener: (listener: RpcMessageListener) => void;
+    readonly addErrorListener: (listener: RpcErrorListener) => void;
+    readonly removeErrorListener: (listener: RpcErrorListener) => void;
+    readonly isOpen: () => boolean;
+    readonly open: () => Promise<void>;
+    readonly close: () => Promise<void>;
+}
+export { RpcMessagePort, RpcMessageDispatch, RpcMessageListener, RpcErrorListener };