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/text-emphasis-position.js

@@ -0,0 +1,14 @@
+let Declaration = require('../declaration')
+
+class TextEmphasisPosition extends Declaration {
+  set(decl, prefix) {
+    if (prefix === '-webkit-') {
+      decl.value = decl.value.replace(/\s*(right|left)\s*/i, '')
+    }
+    return super.set(decl, prefix)
+  }
+}
+
+TextEmphasisPosition.names = ['text-emphasis-position']
+
+module.exports = TextEmphasisPosition