feat(category-icon): 分类图标支持 PNG 资源,学院类目改用 PNG

categorySvgUrlForSlug → categoryAssetUrlForSlug,映射值改为带子目录
的相对路径(svg/ 或 png/),新增 academy-materials / academy-video
的 PNG 图标并兼容拼写别名 acedemy-video。

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/components/CategoryIcon.tsx

@@ -15,7 +15,7 @@ import {
   Play,
   type LucideIcon,
 } from "lucide-react";
-import { categorySvgUrlForSlug } from "../lib/categorySvgSlug";
+import { categoryAssetUrlForSlug } from "../lib/categorySvgSlug";
 
 const map: Record<string, LucideIcon> = {
   folder: Folder,
@@ -40,15 +40,15 @@ export function CategoryIcon({
   className,
 }: {
   iconKey: string;
-  /** When set, prefer branded SVG from `public/assets/ark-library/media/svg/`. */
+  /** When set, prefer branded asset from `public/assets/ark-library/media/`. */
   categorySlug?: string;
   className?: string;
 }) {
-  const svgUrl = categorySlug ? categorySvgUrlForSlug(categorySlug) : null;
-  if (svgUrl) {
+  const assetUrl = categorySlug ? categoryAssetUrlForSlug(categorySlug) : null;
+  if (assetUrl) {
     return (
       <img
-        src={svgUrl}
+        src={assetUrl}
         alt=""
         className={[className, "object-contain pointer-events-none select-none"]
           .filter(Boolean)