fix: 列表封面去重改为兼容当前 TS 目标

app/api/materials/route.ts

@@ -679,7 +679,7 @@ export async function GET(request: NextRequest) {
     const taskPageMissingPreviewIds = materials
       .filter(m => m.materialType === '任务-页面' && !m.previewUrl && !m.videoCoverUrl)
       .map(m => m.id);
-    const coverMaterialIds = [...new Set([...productPackageMaterialIds, ...taskPageMissingPreviewIds])];
+    const coverMaterialIds = Array.from(new Set(productPackageMaterialIds.concat(taskPageMissingPreviewIds)));
     
     const coverUrlMap = new Map<string, string | null>();
     if (coverMaterialIds.length > 0) {