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/@babel/runtime/helpers/esm/toPrimitive.js

@@ -0,0 +1,12 @@
+import _typeof from "./typeof.js";
+function toPrimitive(t, r) {
+  if ("object" != _typeof(t) || !t) return t;
+  var e = t[Symbol.toPrimitive];
+  if (void 0 !== e) {
+    var i = e.call(t, r || "default");
+    if ("object" != _typeof(i)) return i;
+    throw new TypeError("@@toPrimitive must return a primitive value.");
+  }
+  return ("string" === r ? String : Number)(t);
+}
+export { toPrimitive as default };