A failed nightly run left edits in the maintenance clone, and every later run
correctly refused to work on a dirty worktree, so one failure stalled the whole
pipeline until morning.
Maintenance task commands now recognise a gitignored .maintenance-clone marker.
In a marked disposable clone they discard leftover debris, return to main, and
continue; in a human working copy they still stop and touch nothing.
Add an explicit abort protocol: revert your own edits, confirm the worktree is
clean, release the claim, and report. Restore the honest skip that the
complete-file rule had squeezed out, since a laundered fix is worse than a
documented skip, and describe how to handle a file that is entirely an
external-data boundary instead of inventing generic JSON contracts.