Enhance testing suite for mesh collisions

This issue aims to investigate extending the testing suite for mesh collisions. Currently, mesh collision support is **experimental**, and this investigation will help identify gaps and potential improvements to ensure better coverage and reliability.

Start by reviewing the existing testing suite and the current experimental mesh collision support. Identify missing coverage and potential reliability improvements, then document or implement the agreed tests and confirm that mesh collision behavior is covered.

Written by the indexing model from the issue text.