DXF files can have endpoint gaps at entity junctions that fall right at
the floating-point boundary of Tolerance.Epsilon (0.00001). This caused
shapes to not close, resulting in 0 area and 0% utilization in Best-Fit.
Added ChainTolerance (0.0001) for endpoint chaining in GetConnected and
Shape.IsClosed, keeping the tighter Epsilon for geometric precision.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
