Drawings flagged CutFirst (e.g. test squares) are sequenced ahead of
every other part: they get their own route with the chosen method, then
the remaining parts follow. Cutoffs crossing a cut-first part still
precede it. The flag is editable in Edit Drawing, persists in .nest as
`cutFirst` (omitted when false) and is kept by split pieces.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
