The migration from GitHub issues to Gitea runs exactly once, by hand over
the API. Checking a script in for it would leave permanently maintained
code behind for a task that stops existing after its single run - and
worse, it would read to every later visitor as a tool meant to be reused.
A one-off move is carried out once and is history afterwards; it is not a
part of the repository.
The one reference in CLAUDE.md is rewritten rather than deleted: that the
issue numbers do not survive the move is still true and still worth
knowing, so the bullet now says a `#n` in this repo means the GitHub
issue, and that what to do about the old references is open in #225.