Expose Series to OPDS

[SandraCHC]

✨ Feature Request for Booklore

I’m missing my series in the OPDS, similar to calibre-web and other forks.

📝 Description

t would be great if you could add a Series category to your OPDS feed, so that I can browse books by series. Books within the category should be sorted by their series order, so the user knows which one is the first, second, and so on. Maybe with an option to show also the part Number