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/csso/lib/clean/Raw.js

@@ -0,0 +1,9 @@
+var { isNodeChildrenList } = require('./utils');
+
+module.exports = function cleanRaw(node, item, list) {
+    // raw in stylesheet or block children
+    if (isNodeChildrenList(this.stylesheet, list) ||
+        isNodeChildrenList(this.block, list)) {
+        list.remove(item);
+    }
+};