public record PageRequest(int page, int size) {
    public PageRequest {
        if (page < 1) {
            throw new IllegalArgumentException("page must be positive");
        }
        if (size < 1 || size > 100) {
            throw new IllegalArgumentException("size must be between 1 and 100");
        }
    }

    public int offset() {
        return (page - 1) * size;
    }
}