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/middleware.ts

@@ -183,6 +183,6 @@ export async function middleware(req: NextRequest) {
 export const config = {
   // 仅拦截页面与 RSC 请求；/api 由客户端 fetchWithRefresh 处理，静态资源放行
   matcher: [
-    "/((?!api/|_next/static/|_next/image/|favicon.ico|robots.txt|sitemap.xml|.*\\.(?:svg|png|jpg|jpeg|gif|webp|ico|txt|woff2?)$).*)",
+    "/((?!api/|healthz|_next/static/|_next/image/|favicon.ico|robots.txt|sitemap.xml|.*\\.(?:svg|png|jpg|jpeg|gif|webp|ico|txt|woff2?)$).*)",
   ],
 };