Sidewalk displays with incorrect face culling at (-1,5)

## Description Sidewalk at location (-1,5) displays with wrong face culling. Currently the client has no culling implemented, while Foundation recently added backface culling which has not been matched yet. ## Expected Behavior Sidewalk should render with proper backface culling, matching the Foundation client's behavior. ## Screenshots See attached screenshots in Slack thread from Lucas Franca do Nascimento Farias (2026-04-17). ## Steps to Reproduce 1. Navigate to location (-1,5) 2. Observe the sidewalk rendering 3. Notice incorrect face culling (backfaces visible when they should be culled) ## Occurrence 100% - reproducible at this location --- Requested by rob via Slack