Simplify navigation and modernize profile and sign-in

frontend/app/ui/AdminShell.tsx

@@ -1,7 +1,7 @@
 'use client'
 
 import type { ReactNode } from 'react'
-import AdminSidebar from './AdminSidebar'
+import SettingsNavigation from './SettingsNavigation'
 
 type AdminShellProps = {
   title: string
@@ -12,13 +12,9 @@ type AdminShellProps = {
 }
 
 export default function AdminShell({ title, subtitle, actions, rail, children }: AdminShellProps) {
-  const hasRail = Boolean(rail)
-
   return (
-    <div className={`admin-shell ${hasRail ? 'admin-shell--with-rail' : 'admin-shell--no-rail'}`}>
-      <aside className="admin-shell-nav">
-        <AdminSidebar />
-      </aside>
+    <div className="admin-shell admin-shell--top-nav">
+      <SettingsNavigation />
       <main className="card admin-card">
         <div className="admin-header">
           <div>
@@ -29,8 +25,8 @@ export default function AdminShell({ title, subtitle, actions, rail, children }:
           {actions}
         </div>
         {children}
+        {rail && <details className="admin-supplemental"><summary>Additional information</summary>{rail}</details>}
       </main>
-      {hasRail ? <aside className="admin-shell-rail">{rail}</aside> : null}
     </div>
   )
 }