s&box: AI pathfinding with NavMeshAgent — MoveTo, WishVelocity, GetLookAhead

In s&box, AI navigation uses NavMeshAgent component. Developers don't know how to move an agent to a target, read its velocity for animation, or handle the case where UpdatePosition is true vs false. Also, WishVelocity is the correct property to feed into a PlayerController for hybrid AI/physics movement.