feat: add admin links management and updaterup page

- Implemented AdminLinksPage for managing link entries with admin role check.
- Created API routes for fetching, updating, and deleting link entries.
- Added ProductTabs component for navigation between Backerup and Updaterup.
- Developed UpdaterupPage with detailed features, setup instructions, and statistics.
- Introduced links database functionality for runtime-editable link overrides.

frontend/app/admin/AdminTabLinkClient.tsx

@@ -0,0 +1,30 @@
+'use client'
+
+import Link from 'next/link'
+import { usePathname } from 'next/navigation'
+
+export default function AdminTabLinkClient({
+  href,
+  label,
+  exact,
+}: {
+  href: string
+  label: string
+  exact?: boolean
+}) {
+  const pathname = usePathname()
+  const isActive = exact ? pathname === href : pathname.startsWith(href)
+
+  return (
+    <Link
+      href={href}
+      className={`px-4 py-1.5 rounded-lg text-sm font-semibold transition-all ${
+        isActive
+          ? 'bg-violet-500/20 text-violet-300 border border-violet-500/30'
+          : 'text-slate-400 hover:text-slate-200 hover:bg-white/5'
+      }`}
+    >
+      {label}
+    </Link>
+  )
+}