Set default theme to dark

src/App.tsx

@@ -261,7 +261,7 @@ const ShadowFloor = ({ bounds, opacity, rotation, softness }: { bounds: any, opa
 
 export default function App() {
   const [activeSidebar, setActiveSidebar] = useState("Materials");
-  const [theme, setTheme] = useState<"light" | "dark">("light");
+  const [theme, setTheme] = useState<"light" | "dark">("dark");
   const [loadedModel, setLoadedModel] = useState<THREE.Object3D | null>(null);
   const [blobURLs, setBlobURLs] = useState<string[]>([]);