ArchiCOS local modifications to ACadSharp 3.7.1 source snapshot.
Upstream: https://github.com/DomCR/ACadSharp/tree/d7dc111023477d8a9fffc2153139459c95b4f345
Utilities: https://github.com/DomCR/CSUtilities/tree/fdf1403ede6e3376a0baa1deac166cbe4d21262e
Modifications: typed SUN read/write and owner links; same-version VISUALSTYLE property preservation and raw CMC values; lossless preservation of unchanged Unicode XDATA strings; build configuration.
This is a local modified build, not an upstream release. See docs/DWG_CLASSES_0.6.0.md for test scope and limitations.

0.6.1: preserve undocumented FIELDLIST flag on read/write. Raw selective writer in tools/dwg-container-lab preserves original class and handle sections and all bytes outside confirmed replacement spans.

0.6.2: preserve BlockRecord.Preview bytes during DWG serialization. Selective BLOCK_HEADER stale insert-backlink repair with missing-target confirmation against original handle map.
