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/core-js-pure/internals/native-raw-json.js

@@ -0,0 +1,11 @@
+'use strict';
+/* eslint-disable es/no-json -- safe */
+var fails = require('../internals/fails');
+
+module.exports = !fails(function () {
+  var unsafeInt = '9007199254740993';
+  // eslint-disable-next-line es/no-nonstandard-json-properties -- feature detection
+  var raw = JSON.rawJSON(unsafeInt);
+  // eslint-disable-next-line es/no-nonstandard-json-properties -- feature detection
+  return !JSON.isRawJSON(raw) || JSON.stringify(raw) !== unsafeInt;
+});