[Feature] Track production sky rendering delivery

[JeanPhilippeKernel]

Type

• Bug
• Feature
• Refactor / cleanup
• Task / chore

Overview

Track the ordered delivery of a scene-owned, production-grade sky and environment-lighting system.

Context

The implementation follows ZEngine/docs/future-plan/sky-rendering.md. Issue #779 is a closed historical render-graph mode-switching task; the current sequence below is the authoritative implementation plan.

What needs to be done

• [Task] Establish sky renderer resource foundations #799 Establish sky renderer resource foundations
• [Feature] Add scene-owned SkyConfig and editor controls #800 Add scene-owned SkyConfig and editor controls
• [Feature] Add SkyEnvironment snapshots and fallback lifecycle #801 Add SkyEnvironment snapshots and fallback lifecycle
• [Feature] Generate fallback IBL and integrate environment lighting #802 Generate fallback IBL and integrate environment lighting
• [Feature] Implement SkySphere background composition #803 Implement SkySphere background composition
• [Feature] Add HDRI cooking and source-radiance environment maps #804 Add HDRI cooking and source-radiance environment maps
• [Feature] Bake HDRI diffuse and specular image-based lighting #805 Bake HDRI diffuse and specular image-based lighting
• [Feature] Generate static atmosphere LUTs and source radiance #806 Generate static atmosphere LUTs and source radiance
• [Feature] Add per-view sky and aerial-perspective composition #807 Add per-view sky and aerial-perspective composition
• [Feature] Complete atmosphere IBL, validation, and platform capability coverage #808 Complete atmosphere IBL, validation, and platform capability coverage
• [Task] Retire legacy SkyboxPass after sky parity #809 Retire legacy SkyboxPass after sky parity

Resources

• ZEngine/docs/future-plan/sky-rendering.md
• PR feat(rendering): add sky rendering foundations #798

Testing

Each child issue carries focused testing requirements. The final delivery must pass the full renderer validation matrix across supported platforms.

Acceptance criteria

• All delivery issues are completed in dependency order.
• Scene configuration, editor authoring, presentation, and lighting use one documented SkyEnvironment lifecycle.
• The fallback remains valid through loading, failure, hot reload, resize, and revision replacement.
• Builds without warnings in Debug and Release.
• All relevant unit tests pass.
• No regression in existing functionality.

Estimated effort

Multi-PR feature sequence.

[JeanPhilippeKernel]

All ordered sky-rendering delivery issues are now complete through #827.