[Enhancement]: Collapsed series sorting on values other than title

[raviwarrier]

Describe the feature/enhancement

I added two new series: one from Brad Taylor (author) and the by Mathew Peed. The sorting is by date added and so they are displayed after "Jerks at Work" and before "29 Seconds". See image below.

But when I click on "Collapse Series" checkbox, the first book of the series (both of them) doesn't show up between "Jerks at Work" and "29 Seconds". See image below.

All the series are at the end of the list (way below). But shouldn't they be displayed as per the "added at" sorting logic? The last book added in the series should become the "added at" date for the series on the whole.

For example, let's say I have a series "ABC" with 5 books which I uploaded on 01-01-2023. A new 6th book releases today and I add that to my list. The original "added at" date of the series was 01-01-2023, but since I added the new 6th book, the "added at" should be 08-03-2023. And then, I add "Jerks at Work" an hour after I upload the 6th book. So, in the library view with "Collapse Series" on, it should show up between "Jerks at Work" and the book/series I had before I uploaded the latest book in "ABC" series.

This way:

1. The user doesn't have to scroll all the way down OR doesn't have to do a search OR doesn't have to go to Series/Author page to find the latest book (and series).
2. It maintains and honors the sorting preference of the user.
3. It allows users to know that the series was updated (if the "added at" sorting option is selected)

[raviwarrier]

PS: This is also the same issue on the app, but I am assuming since the app just shows webpages, fixing this here would fix it on the app.

[advplyr]

The problem I have with this is the cover that is shown for the series wouldn't always match up with the data that is shown

[advplyr]

Related #957