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/css-tree/lib/common/adopt-buffer.js

@@ -0,0 +1,10 @@
+var MIN_SIZE = 16 * 1024;
+var SafeUint32Array = typeof Uint32Array !== 'undefined' ? Uint32Array : Array; // fallback on Array when TypedArray is not supported
+
+module.exports = function adoptBuffer(buffer, size) {
+    if (buffer === null || buffer.length < size) {
+        return new SafeUint32Array(Math.max(size + 1024, MIN_SIZE));
+    }
+
+    return buffer;
+};