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/app/page.tsx

@@ -172,20 +172,21 @@ export default async function HomePage({ searchParams }: HomePageProps) {
         <WorkspaceNav boards={boards} user={user} />
 
         {/* 中栏：tab 栏与帖子流为同一个整体卡片（左栏切板块只替换这一列） */}
-        <div className="flex-1 min-w-0 relative">
-          {activeBoard ? (
-            <div className="mt-4 lg:mt-0">
-              <SiteDocBreadcrumb
-                items={[
-                  { href: "/", label: "首页" },
-                  { label: activeBoard.name },
-                ]}
-              />
-            </div>
-          ) : null}
+        <div className="flex-1 min-w-0">
           <h1 className="sr-only">{heading}</h1>
 
           <div className="panel overflow-hidden">
+            {activeBoard ? (
+              <div className="px-3 sm:px-4 pt-3">
+                <SiteDocBreadcrumb
+                  className="is-ruled !mb-0"
+                  items={[
+                    { href: "/", label: "首页" },
+                    { label: activeBoard.name },
+                  ]}
+                />
+              </div>
+            ) : null}
             <div className="flex items-center justify-between gap-2 px-3 sm:px-4 pt-3 pb-2.5">
               <FeedTabs current={sort} boardId={boardId} />
               <span className="meta shrink-0 text-[12px] tabular-nums">