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/csso/lib/clean/Declaration.js

@@ -0,0 +1,14 @@
+var property = require('css-tree').property;
+
+module.exports = function cleanDeclartion(node, item, list) {
+    if (node.value.children && node.value.children.isEmpty()) {
+        list.remove(item);
+        return;
+    }
+
+    if (property(node.property).custom) {
+        if (/\S/.test(node.value.value)) {
+            node.value.value = node.value.value.trim();
+        }
+    }
+};