fix(GRO-1822): add role check before /admin redirect — customers access portal

App.tsx lines 389-393 redirected ALL authenticated users to /admin,
breaking customer portal access after SSO login.

Now checks `session.user.role === "staff"` before redirecting.
Customers (role !== "staff") can access the portal at /.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

src/App.tsx

@@ -386,9 +386,10 @@ export function App() {
     return <Navigate to="/setup" replace />;
   }
 
-  // Redirect authenticated users to /admin (but preserve impersonation flow via ?sessionId=)
+  // Redirect staff to /admin; allow customers to access portal (preserve impersonation via ?sessionId=)
   const searchParams = new URLSearchParams(location.search);
-  if (!authDisabled && session && !location.pathname.startsWith("/admin") && !searchParams.has("sessionId")) {
+  const isStaff = session?.user && (session.user as any).role === "staff";
+  if (!authDisabled && session && !location.pathname.startsWith("/admin") && !searchParams.has("sessionId") && isStaff) {
     return <Navigate to="/admin" replace />;
   }