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/own-keys/index.js

@@ -0,0 +1,21 @@
+'use strict';
+
+var GetIntrinsic = require('get-intrinsic');
+
+var safePushApply = require('safe-push-apply');
+
+var $ownKeys = GetIntrinsic('%Reflect.ownKeys%', true);
+var $gOPN = GetIntrinsic('%Object.getOwnPropertyNames%', true);
+var $gOPS = GetIntrinsic('%Object.getOwnPropertySymbols%', true);
+
+var keys = require('object-keys');
+
+/** @type {import('.')} */
+module.exports = $ownKeys || function ownKeys(source) {
+	/** @type {(keyof typeof source)[]} */
+	var sourceKeys = ($gOPN || keys)(source);
+	if ($gOPS) {
+		safePushApply(sourceKeys, $gOPS(source));
+	}
+	return sourceKeys;
+};