Chapters are Character-mapped for unique books

[ShnitzelX2]

Summary

Bugfixes "chapters are character-mapped for unique books"

Purpose of change

Closes #77920

As explained in above issue, books can be copied indefinitely for infinite fun.

Describe the solution

Chapters read for each book itype are mapped per-Character instead of per-item unless "generic": true is added to a book specifying it as a type of book rather than a specific title (e.g. book of essays)

Describe alternatives you've considered

Testing

Read a copy of Dune, noted that another copy had same "chapters read"
Read a (generic = true) Playboy until all the charges were gone, noted a new copy had 4 chapters still left

Read a manual to make sure it still worked

Additional context

Not that it explains much, but you can see the copies of Dune I've read have the same chapters read and the other generic books don't:

[moxian]

Please document the newly added generic field in .md somewhere

More importantly, I'm not very familiar with our save handling, but the lack of explicit de-/serialization of the newly added Character::book_chapters makes me think that this info would be lost after a save-load cycle? Can you please double-check that this part works?

[Procyonae]

Doesn't this still result in the linked issue being present for generic books?

[ShnitzelX2]

So I've fixed:

document the newly added generic field in .md

de-/serialization of the newly added Character::book_chapters

marked as mutable

please add a short comment noting that it represents the amount of chapters remaining in a given book

linked issue being present for generic books

Great reviews, thanks. Double-check if you'd like.

[moxian]

Uh.. do i need to press this approve button here? Still not quite sure how github reviews work, apologies