perf: optimize portfolio runtime delivery

Replace the blocking asset loader with progressive rendering, defer expensive media and Three.js work, and reduce hydration and animation costs. Move deployment from a static Nginx export to the standalone Next.js runtime with optimized dynamic images.

src/components/scenes/AboutRiverScene.tsx

@@ -269,7 +269,7 @@ const createAboutScene: SceneFactory = ({ pointer, theme, reduceMotion }) => {
   };
 };
 
-export function AboutRiverScene() {
+export function AboutRiverScene({ onReady }: { onReady?: () => void }) {
   const { theme } = useTheme();
-  return <ThreeCanvas className={styles.aboutScene} createScene={createAboutScene} theme={theme} />;
+  return <ThreeCanvas className={styles.aboutScene} createScene={createAboutScene} theme={theme} onReady={onReady} />;
 }