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/html-escaper/test/index.js

@@ -0,0 +1,23 @@
+delete Object.freeze;
+
+var html = require('../cjs');
+
+console.assert(
+  html.escape('&<>\'"') === '&amp;&lt;&gt;&#39;&quot;',
+  'correct escape'
+);
+
+console.assert(
+  html.escape('<>\'"&') === '&lt;&gt;&#39;&quot;&amp;',
+  'correct inverted escape'
+);
+
+console.assert(
+  '&<>\'"' === html.unescape('&amp;&lt;&gt;&#39;&quot;'),
+  'correct unescape'
+);
+
+console.assert(
+  '<>\'"&' === html.unescape('&lt;&gt;&#39;&quot;&amp;'),
+  'correct inverted unescape'
+);

node_modules/html-escaper/test/package.json

@@ -0,0 +1 @@
+{"type":"commonjs"}