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/@pmmmwh/react-refresh-webpack-plugin/sockets/WHMEventSource.js

@@ -0,0 +1,31 @@
+/**
+ * The hard-coded singleton key for webpack-hot-middleware's client instance.
+ *
+ * [Ref](https://github.com/webpack-contrib/webpack-hot-middleware/blob/cb29abb9dde435a1ac8e9b19f82d7d36b1093198/client.js#L152)
+ */
+const singletonKey = '__webpack_hot_middleware_reporter__';
+
+/**
+ * Initializes a socket server for HMR for webpack-hot-middleware.
+ * @param {function(*): void} messageHandler A handler to consume Webpack compilation messages.
+ * @returns {void}
+ */
+function initWHMEventSource(messageHandler) {
+  const client = window[singletonKey];
+
+  client.useCustomOverlay({
+    showProblems: function showProblems(type, data) {
+      const error = {
+        data: data,
+        type: type,
+      };
+
+      messageHandler(error);
+    },
+    clear: function clear() {
+      messageHandler({ type: 'ok' });
+    },
+  });
+}
+
+module.exports = { init: initWHMEventSource };