remove the onboarding flow and the accountMode leftover

Onboarding was dead in three layers:

- The OnboardingAdmin screen was only reachable from a route block in App.tsx
  that has been commented out, so it never rendered. Its ServerTypeCard carried
  accountMode ('organization' | 'single'), inherited from the codebase this was
  based on and meaningless for a single-user platform.
- Two /onboarding-complete endpoints, one public and one protected, that no
  frontend code called. Both read a server_config key that was never written, so
  both answered false while the app's own path defaulted to true.
- HomeScreen gated on settings.onboarding.complete to show a welcome panel, and
  seedHomeDir created an Onboarding folder from DATA_PATH/Onboarding and
  /Onboarding_Admin — neither seed directory exists, so it only ever produced an
  empty folder.

Also drops the onboarding key from UserSettings and the now-empty home-header
panel from the default home layout.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/apps/officer-web/App.tsx

@@ -8,7 +8,7 @@ import { useInitialData } from '@/state/useInitialData';
 
 export function App() {
   const { isLoading, isAuthenticated } = useAuth();
-  const { onboardingComplete, plugins, isLoading: isServerSettingsLoading } = useServerSettings();
+  const { plugins, isLoading: isServerSettingsLoading } = useServerSettings();
   useServerEnvironment();
   useInitialData();
 
@@ -26,14 +26,7 @@ export function App() {
           </Routes>
         </Authentication.AuthenticationLayout>
       )}
-      {/* {isAuthenticated && !onboardingComplete && ( */}
-      {/*   <Routes> */}
-      {/*     <Route path="/onboarding-admin" element={<OnboardingAdmin />} /> */}
-      {/*     <Route path="/auth/signout" element={<SignoutScreen />} /> */}
-      {/*     <Route path="*" element={<Navigate to="/onboarding-admin" replace />} /> */}
-      {/*   </Routes> */}
-      {/* )} */}
-      {isAuthenticated && onboardingComplete && (
+      {isAuthenticated && (
         <Dashboard.DashboardLayout>
           <Routes>
             <Route path="/" element={<Dashboard.HomeScreen />} />