[Task] Establish sky renderer resource foundations

[JeanPhilippeKernel]

Type

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

Overview

Provide the generic renderer capabilities required before sky passes can be implemented.

Context

PR #798 implements this work. The sky-rendering design is ZEngine/docs/future-plan/sky-rendering.md, delivery step 0.

What needs to be done

• Share descriptor binding and replay between graphics and compute passes.
• Reflect and bind compute image, sampler, uniform, and storage resources.
• Support true 3D volume textures and render-graph alias compatibility.
• Keep reserved descriptor-set use stage-safe.

Resources

• PR feat(rendering): add sky rendering foundations #798
• ZEngine/docs/future-plan/sky-rendering.md sections 5 and 10

Testing

Build ZEngineTests, run the focused render-graph and PSO suite, and smoke-test SampleProject in the editor.

Acceptance criteria

• PR feat(rendering): add sky rendering foundations #798 is merged.
• Graphics and compute descriptor binding support all sky resource kinds.
• 3D LUT resources are represented as true volume textures.
• Builds without warnings in Debug and Release.
• All relevant unit tests pass.
• No regression in existing functionality.

Estimated effort

Implemented in PR #798.