feat: 交付官方 Docker 运行时，外观改背景图并下线自定义 CSS/JS

站点/后台分轨背景与用户列表排序一并落地；生产 CORS 改走 SITE_URL，健康检查带版本号。

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/components/PinnedPosts.tsx

@@ -44,7 +44,7 @@ export default function PinnedPosts({
           <Link
             key={p.id}
             href={`/post/${p.id}`}
-            className="group relative flex items-center gap-3 sm:gap-3.5 px-4 sm:px-5 py-3.5 transition-colors hover:bg-[var(--panel-2)] focus-visible:bg-[var(--panel-2)] j13-fade-up"
+            className="group relative flex items-center gap-3 sm:gap-3.5 px-4 sm:px-5 py-3.5 transition-colors hover:bg-[var(--item-hover-bg)] focus-visible:bg-[var(--item-hover-bg)] j13-fade-up"
             style={{
               ...(i > 0 ? { borderTop: "1px solid var(--line)" } : {}),
               animationDelay: `${i * 35}ms`,