DEBUG_OVERLAY_Z_INDEX

The zIndex assigned to the PhysicsDebugRenderer's overlay so it sorts above every regular graphics component. Bodies are typically drawn as filled shapes, so an outline rendered beneath them would be completely hidden — the overlay has to win the depth fight against anything in the scene, including bodies spawned at runtime after the renderer was added. A value this large keeps it on top without the caller ever needing to manage the per-object zIndex of their own graphics.