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/autoprefixer/lib/hacks/border-image.js

@@ -0,0 +1,15 @@
+let Declaration = require('../declaration')
+
+class BorderImage extends Declaration {
+  /**
+   * Remove fill parameter for prefixed declarations
+   */
+  set(decl, prefix) {
+    decl.value = decl.value.replace(/\s+fill(\s)/, '$1')
+    return super.set(decl, prefix)
+  }
+}
+
+BorderImage.names = ['border-image']
+
+module.exports = BorderImage