stamp_placeholders (default []) lets a repo declare literals such as TBD that its
restamp replaces with the new version inside a stamp_patterns template. stampOnlyLine
accepts that move only on a branch line named by position; finish's stampedFiles,
the receipt carry and the tree receipt share it. The carried receipt's version is
HEAD's, read the way write reads it.
Co-authored-by: capy-ai[bot] <230910855+capy-ai[bot]@users.noreply.github.com>