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/webpack-dev-server/client/utils/sendMessage.js

@@ -0,0 +1,16 @@
+/* global __resourceQuery WorkerGlobalScope */
+
+// Send messages to the outside, so plugins can consume it.
+/**
+ * @param {string} type
+ * @param {any} [data]
+ */
+function sendMsg(type, data) {
+  if (typeof self !== "undefined" && (typeof WorkerGlobalScope === "undefined" || !(self instanceof WorkerGlobalScope))) {
+    self.postMessage({
+      type: "webpack".concat(type),
+      data: data
+    }, "*");
+  }
+}
+export default sendMsg;