Add notification if a book from my "want to read" list becomes available

When correcting existing books, I noticed several user lists that were called something like "Books I want to read but are not available on Open Library". Sometimes, those lists contained books that became available meanwhile, or where they were available but where not found due to duplicate entries.

### Describe the problem that you'd like solved

It would be very cool if I could get some kind of notification if a book I want to read became available - either because it was recently scanned or because a merge connects a book on my list with an existing ebook in my language.

### Proposal & Constraints

The "unread mails" notification of email clients work a little bit like this.

Ideally, the notification would be somehow connected to the display of my reading list, thus I would see a small exclamation mark for "new books available" in front of my reading list (like the "new unread mail" icon in mail clients) and the ability to filter for those newly available books (like the "show only unread mail" function in email clients).

Implementing this is probably difficult, as it need to check for merges, scans and language, all of which are not currently easily accessible as far as I am aware. Especially language is a problem, as many entries simply lack language information.

### Additional context

### Stakeholders

Users with a "want to read" list.