Restrict AI features to administrators only for improved control

Update routes and sidebar to enforce admin-only access for AI features, including model retrieval, text generation, and history viewing.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: ae4037a0-2a6f-4530-9bac-79b543286bda
Replit-Commit-Checkpoint-Type: intermediate_checkpoint
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/397bca8c-984f-43ff-841a-10897aeb8140/ae4037a0-2a6f-4530-9bac-79b543286bda/G1P4XGr

client/src/App.tsx

@@ -69,7 +69,7 @@ function Router() {
       <Route path="/calendar">{() => <ProtectedRoute component={Calendar} />}</Route>
       <Route path="/media">{() => <ProtectedRoute component={Media} />}</Route>
       <Route path="/pages">{() => <ProtectedRoute component={PagesManagement} />}</Route>
-      <Route path="/ai">{() => <ProtectedRoute component={AI} />}</Route>
+      <Route path="/ai">{() => <ProtectedRoute component={AI} adminOnly />}</Route>
       <Route path="/history">{() => <ProtectedRoute component={History} />}</Route>
       <Route path="/settings">{() => <ProtectedRoute component={Settings} adminOnly />}</Route>
       <Route path="/sql">{() => <ProtectedRoute component={SqlAdmin} adminOnly />}</Route>