Add curator authentication with audit logging and fix empty 3D gallery sessions.

Introduce session-based curator login, gate debug/checkup routes, log mutations to curator_audit_log, and keep guest hall preload public. Fix gallery view mounting so WebGL halls render reliably after navigation.

client/src/main.tsx

@@ -2,9 +2,12 @@ import { StrictMode } from 'react'
 import { createRoot } from 'react-dom/client'
 import './index.css'
 import App from './App.tsx'
+import { AuthProvider } from './context/AuthContext.tsx'
 
 createRoot(document.getElementById('root')!).render(
   <StrictMode>
-    <App />
+    <AuthProvider>
+      <App />
+    </AuthProvider>
   </StrictMode>,
 )