RemnantFiller removes the topmost placed part to keep a clean rectangular
obstacle for the next drawing, but the envelope then walls that slot off,
so the part was lost for nothing (4 squares on a 9x9 plate became 3).
Only remove it while another drawing still has demand.
Fixes the mixed-stock NestRunner tests.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
ajandClaude Sonnet 5
630d514b0e