Every R3D_* read goes through r3d_env_has / r3d_env (env.ludic): a headless
build honours them as before, a windowed build only when R3D_DEV is set to
anything but "0", so a shipped game never reaches a debug view, feature kill,
file writer or hardware fake. Documented in docs/SHIPPING.md.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
