The empty new-plate header read only "New plate (empty)", so the sheet
size of the plate about to be nested was hidden until parts were added.
FormatHeader now appends the size (and quantity above one) there too.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
The editor header and the Plan Cutting dialog counted the trailing empty
new-plate workspace PlateManager.EnsureSentinel maintains, so a one-plate
nest read 'Plate 1 of 2'. PlateDisplayNumbering now derives display-only
numbers that exclude only a trailing empty sentinel; interior empty plates
keep their slot and number, and navigation, storage indexes, exported
names and batch selection are untouched. The sentinel itself is labeled
'New plate (empty)' instead of being numbered beyond the shown total.