New EngineOverlapTests verifies all engine types produce overlap-free
results. New StrategyOverlapTests checks each fill strategy individually.
StripeFillerTests updated to verify returned parts are overlap-free
rather than just asserting non-empty results. Remove obsolete FitCircle
tests from GeometrySimplifierTests (method was removed).
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
The convergence loop now ensures the pair starts with its short side
parallel to the primary axis, maximizing the number of pairs that fit.
Also adds ConvergeStripeAngleShrink to try N+1 narrower pairs, and
evaluates both expand and shrink results to pick the better grid.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
aj