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/convertor/create.js

@@ -0,0 +1,28 @@
+var List = require('../common/List');
+
+module.exports = function createConvertors(walk) {
+    return {
+        fromPlainObject: function(ast) {
+            walk(ast, {
+                enter: function(node) {
+                    if (node.children && node.children instanceof List === false) {
+                        node.children = new List().fromArray(node.children);
+                    }
+                }
+            });
+
+            return ast;
+        },
+        toPlainObject: function(ast) {
+            walk(ast, {
+                leave: function(node) {
+                    if (node.children && node.children instanceof List) {
+                        node.children = node.children.toArray();
+                    }
+                }
+            });
+
+            return ast;
+        }
+    };
+};

node_modules/css-tree/lib/convertor/index.js

@@ -0,0 +1,3 @@
+var createConvertor = require('./create');
+
+module.exports = createConvertor(require('../walker'));