Comprehensive spec for completing the physics/movement system:
CellPortal-based indoor/outdoor/room-to-room transitions via
sphere-plane intersection, multi-landblock boundary crossing,
momentum-preserving jump with gravity arc, portal-space state
machine for teleports, Setup.StepUpHeight hookup, and
scenery-on-road exclusion fix.
Replaces the current "outdoor heightmap sampler with disabled
indoor transitions" with the full world-navigation system AC's
client uses. 12 acceptance criteria, ~20 new unit tests planned.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
