feat: add needsVehicleSelection frontend hook (refs #60)

- Add NeedsVehicleSelectionResponse type
- Add needsVehicleSelection API method
- Add useNeedsVehicleSelection hook with staleTime: 0

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/src/features/subscription/hooks/useSubscription.ts

@@ -19,6 +19,17 @@ export const useSubscription = () => {
   });
 };
 
+export const useNeedsVehicleSelection = () => {
+  const { isAuthenticated, isLoading } = useAuth0();
+
+  return useQuery({
+    queryKey: ['needs-vehicle-selection'],
+    queryFn: () => subscriptionApi.needsVehicleSelection(),
+    enabled: isAuthenticated && !isLoading,
+    staleTime: 0, // Always fetch fresh on login
+  });
+};
+
 export const useCheckout = () => {
   const queryClient = useQueryClient();
   return useMutation({