Feature that moves old posts from X into a mixi2 calendar, criteria set by the development team(zenn.dev)

- This feature saves old posts from the ZIP archive downloaded from X as mixi2 posts. According to the original text, saved posts can be viewed again by date in the mixi2 calendar. - According to the original text, posts are saved with the date they were posted on X, but they are excluded from follower timeline distribution, notifications, and consecutive posting day counts. The design aims to prevent old posts from filling timelines all at once. - According to the original text, the archive is not loaded entirely into server memory. It is uploaded directly to S3, then opened as a file with S3 Files so that only the needed parts are read. Posts are processed in asynchronous jobs in batches of up to 1,000. - The original text states that a mapping table between X post IDs and mixi2 post IDs is written in the same transaction to prevent duplicate saves on rerun. The policy is to keep processing the remaining posts even if an individual post fails. The part where past dates are reflected in search results is not yet complete, as the author says it is currently being addressed.