Design a Bookshelf with Book CRUD and a Stable Bookmark

You are designing an object-oriented bookshelf service. It must provide CRUD operations for books (create, read, update, delete) and must also maintain a bookmark. The statement intentionally leaves the meaning of the bookmark open: it could refer to a book, a location inside a book, or a position between books. Your first responsibility is to state which interpretation you are using, then define the classes and operations for that contract. The model must explain how the…