Add car reordering and AM/PM period for reservations

Agent-Logs-Url: https://github.com/pdf114514/CarReservation/sessions/c0a4b7dc-228e-4e7d-a985-61b9a17de159

Co-authored-by: pdf114514 <57948770+pdf114514@users.noreply.github.com>

frontend/src/api.js

@@ -23,6 +23,7 @@ export const api = {
   createCar: (data) => request('/cars', { method: 'POST', body: JSON.stringify(data) }),
   updateCar: (id, data) => request(`/cars/${id}`, { method: 'PUT', body: JSON.stringify(data) }),
   deleteCar: (id) => request(`/cars/${id}`, { method: 'DELETE' }),
+  reorderCars: (ids) => request('/cars/reorder', { method: 'PUT', body: JSON.stringify({ ids }) }),
 
   // Reservations
   getReservations: () => request('/reservations'),