Port box's drill-recorded.sh (the origin of the three copies) as a
composite action on the #5 pattern: version read through lib/version.sh,
one file per version under drills/, whitespace-only records refused.
Keyed on the tree's version — -dev trees pass with a notice that says
why nothing was asserted; bare trees must show drills/<version>.md with
at least one non-whitespace character.
Closes#7
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
