feat: refine wooden fish runtime generation

src/components/wooden-fish-runtime/WoodenFishRuntimeShell.tsx

@@ -95,6 +95,10 @@ export function WoodenFishRuntimeShell({
     profile?.hitObjectAsset?.imageSrc?.trim() ||
     profile?.draft.hitObjectAsset?.imageSrc?.trim() ||
     WOODEN_FISH_DEFAULT_HIT_OBJECT_SRC;
+  const backgroundSrc =
+    profile?.backgroundAsset?.imageSrc?.trim() ||
+    profile?.draft.backgroundAsset?.imageSrc?.trim() ||
+    '';
   const hitSoundSrc =
     profile?.hitSoundAsset?.audioSrc ?? profile?.draft.hitSoundAsset?.audioSrc;
   const { resolvedUrl: resolvedAudioUrl } = useResolvedAssetReadUrl(hitSoundSrc);
@@ -217,6 +221,16 @@ export function WoodenFishRuntimeShell({
       onPointerDown={registerTap}
     >
       <div className="pointer-events-none absolute inset-0 bg-[radial-gradient(circle_at_50%_18%,rgba(255,255,255,0.92),transparent_26%),linear-gradient(180deg,#fff8e8_0%,#eef7ed_55%,#e5f2f7_100%)]" />
+      {backgroundSrc ? (
+        <ResolvedAssetImage
+          src={backgroundSrc}
+          alt=""
+          aria-hidden="true"
+          draggable={false}
+          className="pointer-events-none absolute inset-0 h-full w-full object-cover"
+        />
+      ) : null}
+      <div className="pointer-events-none absolute inset-0 bg-white/10" />
 
       <header
         data-wooden-fish-functional="true"