feat: Replace nav title with back to dashboard link

- Remove "NexusGate Docs" text from sidebar header
- Add NavTitle component with "返回控制台/Back to Dashboard" link
- Remove sidebar banner (no longer needed)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: pescn

src/components/nav-title.tsx

@@ -0,0 +1,22 @@
+'use client';
+
+import { ArrowLeft } from 'lucide-react';
+
+interface NavTitleProps {
+  locale?: string;
+}
+
+export function NavTitle({ locale }: NavTitleProps) {
+  const isZh = locale === 'zh';
+
+  // Use relative path to go up from /docs/ to root /
+  return (
+    <a
+      href="/"
+      className="flex items-center gap-2 text-sm font-medium text-fd-foreground transition-colors hover:text-fd-foreground/80"
+    >
+      <ArrowLeft className="size-4" />
+      {isZh ? '返回控制台' : 'Back to Dashboard'}
+    </a>
+  );
+}

src/lib/layout.shared.tsx

@@ -1,15 +1,12 @@
 import type { DocsLayoutProps } from 'fumadocs-ui/layouts/docs';
-import { SidebarBanner } from '@/components/sidebar-banner';
+import { NavTitle } from '@/components/nav-title';
 import { i18n } from './i18n';
 
 export function baseOptions(locale: string): Omit<DocsLayoutProps, 'tree' | 'children'> {
   return {
     i18n,
     nav: {
-      title: 'NexusGate Docs',
-    },
-    sidebar: {
-      banner: <SidebarBanner locale={locale} />,
+      title: <NavTitle locale={locale} />,
     },
   };
 }