- Adds a "What it looks like" section to the pre-edit hook page: the editor
before (the user's own filter, one quarter of rows) and after (the hook's
widened filter, both quarters), captured from the mocked estate.
- Corrects the re-read step: it now drops &drop_rk like getdata does, and the
accompanying note records that a bitemporal table also needs the latest-record
dedup, so the example no longer claims to mirror getdata exactly while missing
both (raised in review of #16).
