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/braces/lib/stringify.js

@@ -0,0 +1,32 @@
+'use strict';
+
+const utils = require('./utils');
+
+module.exports = (ast, options = {}) => {
+  const stringify = (node, parent = {}) => {
+    const invalidBlock = options.escapeInvalid && utils.isInvalidBrace(parent);
+    const invalidNode = node.invalid === true && options.escapeInvalid === true;
+    let output = '';
+
+    if (node.value) {
+      if ((invalidBlock || invalidNode) && utils.isOpenOrClose(node)) {
+        return '\\' + node.value;
+      }
+      return node.value;
+    }
+
+    if (node.value) {
+      return node.value;
+    }
+
+    if (node.nodes) {
+      for (const child of node.nodes) {
+        output += stringify(child);
+      }
+    }
+    return output;
+  };
+
+  return stringify(ast);
+};
+