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/node/Brackets.js

@@ -0,0 +1,34 @@
+var TYPE = require('../../tokenizer').TYPE;
+
+var LEFTSQUAREBRACKET = TYPE.LeftSquareBracket;
+var RIGHTSQUAREBRACKET = TYPE.RightSquareBracket;
+
+module.exports = {
+    name: 'Brackets',
+    structure: {
+        children: [[]]
+    },
+    parse: function(readSequence, recognizer) {
+        var start = this.scanner.tokenStart;
+        var children = null;
+
+        this.eat(LEFTSQUAREBRACKET);
+
+        children = readSequence.call(this, recognizer);
+
+        if (!this.scanner.eof) {
+            this.eat(RIGHTSQUAREBRACKET);
+        }
+
+        return {
+            type: 'Brackets',
+            loc: this.getLocation(start, this.scanner.tokenStart),
+            children: children
+        };
+    },
+    generate: function(node) {
+        this.chunk('[');
+        this.children(node);
+        this.chunk(']');
+    }
+};