Fix spurious new-assessment log entries for renamed articles

[arnchlmcodes]

Heyy @audiodude During update_project_assessments_by_kind, any article whose ref is absent from old_ratings gets treated as new. The problem is that a renamed article will always look new at this stage because the old name is what's stored in old_ratings, not the new one. Previously, store_new_ratings would immediately call add_log_for_rating for these, writing a spurious log entry with old_rating_value defaulting to NotA-Class.

The fix defers those log entries into a list instead of writing them immediately. Only articles that already existed in old_ratings but had a rating change get logged right away, since an existing ref changing its rating cannot be a rename.

process_unseen_articles runs after both quality and importance passes complete. For each old ref that wasn't seen, it calls get_move_data() to check if the article was renamed. If a move is detected, the destination ref is added to a moved_articles set. Back in update_project_assessments, the deferred logs are then written only for refs not present in moved_articles, ensuring that renamed articles don't get a spurious new-assessment log entry while genuinely new articles are logged correctly.

fixes issue #72

let me know if the fix is correct, I'll start working on the test cases next.

[audiodude]

This looks great! Please add the tests now.