fix: 客户端资源清理 — ShareCard 依赖 + 定时器 + 死代码

- #20: ShareCardModal useEffect 依赖改为 imageSrc 字符串，避免对象引用变化重复加载
- #21: BlindboxRoomPage 所有 setTimeout/rAF 统一收集，unmount 时清理
- #25: 删除未使用的 confettiCanvasRef 和 canvas 元素

src/components/ShareCardModal.tsx

@@ -38,21 +38,20 @@ export default function ShareCardModal({
   const [imageDataUrl, setImageDataUrl] = useState<string | null>(null);
   const [imageLoading, setImageLoading] = useState(false);
 
+  const imageSrc = data.type === "restaurant" ? data.restaurant.images?.[0] : undefined;
+
   useEffect(() => {
     if (!open) {
       setImageDataUrl(null);
       return;
     }
-    if (data.type !== "restaurant") return;
-
-    const src = data.restaurant.images?.[0];
-    if (!src) return;
+    if (!imageSrc) return;
 
     setImageLoading(true);
-    loadImageAsDataUrl(src)
+    loadImageAsDataUrl(imageSrc)
       .then(setImageDataUrl)
       .finally(() => setImageLoading(false));
-  }, [open, data]);
+  }, [open, imageSrc]);
 
   const handleGenerate = useCallback(async (): Promise<string | null> => {
     if (!cardRef.current) return null;