Merge origin/main and retain both format-scope additions.
Give StarrySky a separate black environment cube map and release it on destroy.
Guard anime updates when StarrySky is absent, require a visible Normal sky
before anime QA, and compare a lit airplane against black and white controls.
Document the sky background contract and its verification.
Co-Authored-By: GPT-6 (Codex) <[email protected]>
