As a user, I want to reserve a book for loan, so that I can read it.

## User Story:
>- As a user, I want to reserve a book for loan, so that I can read it.

## Steps for Demonstration:
>- The user goes to the details page of the desired book.
>- Click the "Reserve for Loan" button, if available.
>- Show the confirmation popup that the book has been reserved.

## Acceptance Criteria:
>- Users must be clearly shown the confirmation message.
>- Users must not have more than 5 ongoing reservations.
>- The book must be available.
>- Errors should be displayed in the same popup.

## Result:
>- Successful reservation of a loan.