feat: implement admin dashboard with site settings, user management, and activity monitoring

frontend/src/App.tsx

@@ -11,6 +11,7 @@ import TweaksPanel from './components/TweaksPanel'
 import AuthModal from './components/AuthModal'
 import EmailVerify from './components/EmailVerify'
 import ResetPassword from './components/ResetPassword'
+import AdminDashboard from './components/AdminDashboard'
 
 const DEFAULT_TWEAKS: Tweaks = { theme: 'light', fontSize: 'medium', feedbackMode: 'auto' }
 
@@ -38,6 +39,8 @@ function AppInner() {
       setScreen('verify')
     } else if (path === '/reset-password') {
       setScreen('reset-password')
+    } else if (path === '/admin') {
+      setScreen('admin')
     }
   }, [])
 
@@ -263,16 +266,21 @@ function AppInner() {
                 {user.displayName.charAt(0).toUpperCase()}
               </button>
               {userMenuOpen && (
-                <div className="user-menu">
-                  <div className="user-menu-header">
-                    <div className="user-menu-name">{user.displayName}</div>
-                    <div className="user-menu-email">{user.email}</div>
+                  <div className="user-menu">
+                    <div className="user-menu-header">
+                      <div className="user-menu-name">{user.displayName}</div>
+                      <div className="user-menu-email">{user.email}</div>
+                    </div>
+                    <div className="user-menu-divider" />
+                    {user.role === 'admin' && (
+                      <button className="user-menu-item" onClick={() => { setUserMenuOpen(false); setScreen('admin'); globalThis.history.pushState({}, '', '/admin') }}>
+                        Admin Dashboard
+                      </button>
+                    )}
+                    <button className="user-menu-item" onClick={() => { setUserMenuOpen(false); logout() }}>
+                      Sign Out
+                    </button>
                   </div>
-                  <div className="user-menu-divider" />
-                  <button className="user-menu-item" onClick={() => { setUserMenuOpen(false); logout() }}>
-                    Sign Out
-                  </button>
-                </div>
               )}
             </div>
           )}
@@ -282,6 +290,9 @@ function AppInner() {
       {screen === 'landing' && (
         <Landing onLoadExam={loadExam} history={history} onResume={resume} onClearHistory={clearAllHistory} onReviewAttempt={reviewAttempt} />
       )}
+      {screen === 'admin' && user?.role === 'admin' && (
+        <AdminDashboard onExit={exit} />
+      )}
       {screen === 'exam' && exam && examState && (
         <ExamRunner exam={exam} state={examState} setState={setExamStateStrict} onSubmit={submit} onExit={exit} />
       )}