feat(admin): sidebar shell + routing

apps/admin/src/App.tsx

@@ -1,9 +1,24 @@
+import { BrowserRouter, Route, Routes } from 'react-router-dom';
 import { AuthProvider, useAuth } from './auth/AuthContext';
 import Login from './screens/Login';
+import Sidebar from './components/Sidebar';
+import Live from './screens/Live';
+import Activities from './screens/Activities';
 
 function AuthedShell() {
-  // Placeholder shell — replaced by the sidebar + routing in Task 4.
-  return <div>SoleLog Admin</div>;
+  return (
+    <BrowserRouter>
+      <div className="admin-shell">
+        <Sidebar />
+        <main className="admin-main">
+          <Routes>
+            <Route path="/" element={<Live />} />
+            <Route path="/handelingen" element={<Activities />} />
+          </Routes>
+        </main>
+      </div>
+    </BrowserRouter>
+  );
 }
 
 function Gate() {