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/importDeferProxy.js

@@ -0,0 +1,27 @@
+function _importDeferProxy(e) {
+  var t = null,
+    constValue = function constValue(e) {
+      return function () {
+        return e;
+      };
+    },
+    proxy = function proxy(r) {
+      return function (n, o, f) {
+        return null === t && (t = e()), r(t, o, f);
+      };
+    };
+  return new Proxy({}, {
+    defineProperty: constValue(!1),
+    deleteProperty: constValue(!1),
+    get: proxy(Reflect.get),
+    getOwnPropertyDescriptor: proxy(Reflect.getOwnPropertyDescriptor),
+    getPrototypeOf: constValue(null),
+    isExtensible: constValue(!1),
+    has: proxy(Reflect.has),
+    ownKeys: proxy(Reflect.ownKeys),
+    preventExtensions: constValue(!0),
+    set: constValue(!1),
+    setPrototypeOf: constValue(!1)
+  });
+}
+export { _importDeferProxy as default };