WGSL implementation of soft shadows

[mvaligursky]

• soft shadows works using WGSL
• fixed few other issues in WGSL chunks this example exposed

[Copilot]

Pull Request Overview

This pull request implements soft shadows using WGSL along with a few fixes in shadow and depth linearization functions.

• Updated depth linearization functions to use the new linearizeDepthWithParams API.
• Replaced conventional saturate and gamma-correction functions with their WGSL-specific counterparts (saturate3 and gammaCorrectInputVec3).
• Introduced a new WGSL implementation for soft shadows and adjusted shader chunk imports accordingly.

Reviewed Changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/scene/shader-lib/chunks/lit/frag/pass-shadow/litShadowMain.js	Updated to call linearizeDepthWithParams for improved depth calculations.
src/scene/shader-lib/chunks/lit/frag/lighting/shadowSoft.js	Removed the extraneous numRings parameter from prepareDiskConstants and updated related calls.
src/scene/shader-lib/chunks/lit/frag/lighting/shadowPCSS.js	Replaced linearizeDepth with linearizeDepthWithParams for consistency.
src/scene/shader-lib/chunks/common/frag/linearizeDepth.js	Renamed depth linearization function to linearizeDepthWithParams and updated alias usage.
src/scene/shader-lib/chunks-wgsl/standard/frag/specular.js src/scene/shader-lib/chunks-wgsl/standard/frag/sheen.js src/scene/shader-lib/chunks-wgsl/standard/frag/emissive.js src/scene/shader-lib/chunks-wgsl/standard/frag/diffuse.js	Changed shader functions to use saturate3 and gammaCorrectInputVec3 variants per new WGSL practices.
src/scene/shader-lib/chunks-wgsl/lit/frag/pass-shadow/litShadowMain.js	Mirrored the depth linearization update in WGSL shaders.
src/scene/shader-lib/chunks-wgsl/lit/frag/lighting/shadowSoft.js	Added a complete WGSL implementation for soft shadows using PCSS with updated disk sampling routines.
src/scene/shader-lib/chunks-wgsl/lit/frag/lighting/lighting.js	Adjusted shader chunk imports and added comments regarding unsupported omni/spot PCSS on WebGPU.
src/scene/shader-lib/chunks-wgsl/lit/frag/lighting/lightFunctionShadow.js	Minor formatting adjustments in light shadow function logic.
src/scene/shader-lib/chunks-wgsl/lit/frag/cubeMapRotate.js	Updated cube map rotation to reference a uniform variable.
src/scene/shader-lib/chunks-wgsl/common/frag/linearizeDepth.js	Introduced a new WGSL depth linearization file matching the updated API conventions.
src/scene/shader-lib/chunks-wgsl/chunks-wgsl.js	Updated shader chunk imports to reflect the recent WGSL function and file changes.

Comments suppressed due to low confidence (1)

src/scene/shader-lib/chunks-wgsl/lit/frag/lighting/shadowSoft.js:85

• Ensure that 'pcPosition' is defined and properly passed as a shader input since it's used to generate the random seed.

let randomSeed: f32 = fractSinRand(pcPosition.xy);