Consolidate theme radius/shadow props and make rounded utilities responsive

- Remove duplicate roundedness/shadowLevel props (keep radius/shadow)
- Switch globals.css radius scale to proportional (square→pill works)
- Replace rounded-full with rounded-md on theme-driven elements
- Remove banner props from Navigation, drop publishing overlay

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/App.tsx

@@ -101,11 +101,6 @@ export default function App() {
           }}
         />
       </ShopifyProvider>
-      {isPublishing && (
-        <div className="fixed inset-0 z-[9999] flex items-center justify-center bg-black/30">
-          <Loader size={32} />
-        </div>
-      )}
     </div>
   );
 }