fix: show tab bar in native app (Flutter doesn't render its own)

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

public/css/core.css

@@ -446,8 +446,5 @@ body::before {
 ::-webkit-scrollbar-track { background: transparent; }
 ::-webkit-scrollbar-thumb { background: var(--border-hover); border-radius: 2px; }
 
-/* Native App Mode — Flutter renders the bottom nav */
-.native-app .bottom-nav,
-.native-app .tab-bar { display: none !important; }
-.native-app #scene-container { bottom: 0 !important; }
-.native-app body { padding-bottom: 0 !important; }
+/* Native App Mode */
+.native-app .bottom-nav { display: none !important; }