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/syntax/index.js

@@ -0,0 +1,20 @@
+function merge() {
+    var dest = {};
+
+    for (var i = 0; i < arguments.length; i++) {
+        var src = arguments[i];
+        for (var key in src) {
+            dest[key] = src[key];
+        }
+    }
+
+    return dest;
+}
+
+module.exports = require('./create').create(
+    merge(
+        require('./config/lexer'),
+        require('./config/parser'),
+        require('./config/walker')
+    )
+);