feat: add mobile shadcn admin navigation

frontend/src/app/layout/AppShell.tsx

@@ -1,4 +1,4 @@
-import type * as React from 'react'
+import * as React from 'react'
 
 import { AppSidebar } from '@/components/app/AppSidebar'
 import { AppTopbar } from '@/components/app/AppTopbar'
@@ -8,11 +8,13 @@ type AppShellProps = {
 }
 
 export function AppShell({ children }: AppShellProps) {
+  const [mobileNavOpen, setMobileNavOpen] = React.useState(false)
+
   return (
     <div className="min-h-screen bg-background text-foreground">
-      <AppSidebar />
+      <AppSidebar mobileOpen={mobileNavOpen} onMobileOpenChange={setMobileNavOpen} />
       <div className="min-h-screen lg:pl-72">
-        <AppTopbar />
+        <AppTopbar onMobileMenuClick={() => setMobileNavOpen(true)} />
         {children}
       </div>
     </div>