StepUpHeight: when Tab enters player mode, read Setup.StepUpHeight from the
player entity's dat and apply it to the controller (fallback 2f for non-Setup
entities or when the dat value is zero). Previously hardcoded to 5.0 which
made step-up too permissive.
Road exclusion: SceneryGenerator now skips terrain vertices where bits 0-1 of
the raw terrain word are non-zero. These bits encode the road type (GetRoad()
in ACViewer's Landblock.cs). Trees, rocks and bushes will no longer be placed
on road surfaces.
Added SceneryGenerator.IsRoadVertex(ushort) public helper + 9 unit tests
(theory + fact) verifying the road-bit convention matches TerrainInfo.Road.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
