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/postcss-value-parser/lib/walk.js

@@ -0,0 +1,22 @@
+module.exports = function walk(nodes, cb, bubble) {
+  var i, max, node, result;
+
+  for (i = 0, max = nodes.length; i < max; i += 1) {
+    node = nodes[i];
+    if (!bubble) {
+      result = cb(node, i, nodes);
+    }
+
+    if (
+      result !== false &&
+      node.type === "function" &&
+      Array.isArray(node.nodes)
+    ) {
+      walk(node.nodes, cb, bubble);
+    }
+
+    if (bubble) {
+      cb(node, i, nodes);
+    }
+  }
+};