Move admin state into AdminPage

All admin state (tab, users, projects, loading/error, preview, reset
result) and the data loader were only used by AdminPage, so they now live
there as local state instead of in App's context. The page loads its data
when it opens (still gated on authUser.isAdmin; the server enforces it too).

Add tests: admin sees users and projects, deleting a user reloads the
list, and non-admins get no Admin button.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/App.jsx

@@ -47,8 +47,6 @@ import {
   enableSharing,
   disableSharing,
   getSharedProject,
-  adminListUsers,
-  adminListProjects,
 } from './syncService.js';
 
 // Less-common pages are split into their own chunks so the first load only
@@ -89,14 +87,6 @@ const App = () => {
   const [sharedViewToken] = useState(() => new URLSearchParams(window.location.search).get('share'));
   const [sharedProject, setSharedProject] = useState(null);
   const [sharedError, setSharedError] = useState('');
-  // Admin (only reachable/rendered when authUser.isAdmin)
-  const [adminTab, setAdminTab] = useState('users'); // 'users' | 'projects'
-  const [adminUsers, setAdminUsers] = useState([]);
-  const [adminProjects, setAdminProjects] = useState([]);
-  const [adminLoading, setAdminLoading] = useState(false);
-  const [adminError, setAdminError] = useState('');
-  const [adminViewProject, setAdminViewProject] = useState(null); // full project data being previewed
-  const [adminResetResult, setAdminResetResult] = useState(null); // { email, temporaryPassword } shown once
   const [project, setProject] = useState(null);
   // 'home' | 'setup' | 'study' | 'settings'
   const [currentPage, setCurrentPage] = useState('home');
@@ -301,24 +291,6 @@ const App = () => {
     });
   }, [project?.id, currentPage]);
 
-  const loadAdminData = () => {
-    setAdminLoading(true);
-    setAdminError('');
-    Promise.all([adminListUsers(), adminListProjects()]).then(([usersResult, projectsResult]) => {
-      setAdminLoading(false);
-      if (!usersResult.ok || !projectsResult.ok) {
-        setAdminError(usersResult.error ?? projectsResult.error ?? 'Failed to load admin data.');
-        return;
-      }
-      setAdminUsers(usersResult.data);
-      setAdminProjects(projectsResult.data);
-    });
-  };
-
-  useEffect(() => {
-    if (currentPage === 'admin' && authUser?.isAdmin) loadAdminData();
-  }, [currentPage, authUser?.isAdmin]);
-
   // Once we know who's signed in, reconcile the local project index against the server.
   // Runs on every authUser change (including logout -> different login) so a previous
   // account's stale suggestions never linger after switching users. Projects that exist
@@ -2291,15 +2263,6 @@ const deleteProject = (id) => {
     speakOriginalWord,
     loadVerseText,
     importFinalScriptDocx,
-    // Admin
-    adminTab, setAdminTab,
-    adminUsers,
-    adminProjects,
-    adminLoading,
-    adminError,
-    adminViewProject, setAdminViewProject,
-    adminResetResult, setAdminResetResult,
-    loadAdminData,
     // Functions defined inside App (cannot be module-level exports)
     formatCrossRef,
     buildGreekDefinitionHtml,