fix(WebGPU): apply projection once in ImageMapper and refresh imageData textures

[sedghi]

Context

The WebGPU ImageMapper vertex shader applies rendererUBO.SCPCMatrix twice (regression from 7fbc87a). With close-in cameras — e.g. a parallel camera one unit in front of the slice, as medical viewers set up — the doubly-projected quad falls outside the clip volume and the slice silently renders nothing. The same commit also stores a clip-space position in vertexSC, which the clip-plane code expects in stabilized coordinates.

Separately, TextureManager.getTextureForImageData keys its texture cache on the scalar array mtime alone, so writing scalars in place and signaling with imageData.modified() (the invalidation the OpenGL backend keys texture rebuilds on) keeps returning the stale texture.

Both were found while rendering image stacks on the WebGPU view API from Cornerstone3D.

Results

• Image slices render again with offset parallel cameras (before: nothing drawn; reproducible with the ImageMapper example and ?viewAPI=WebGPU).
• Clip planes on ImageMapper are evaluated in stabilized coordinates again.
• Textures refresh when scalars are updated in place and only imageData.modified() is called.

Changes

• WebGPU/ImageMapper: capture vertexSC before projecting, apply SCPCMatrix once (matches ImageResliceMapper/ImageCPRMapper).
• WebGPU/TextureManager: key the getTextureForImageData cache on the newest of the imageData and scalar array mtimes.
• vitest.config.js: pass --enable-unsafe-webgpu to headless Chromium for WEBGPU=1 runs (plus the SwiftShader WebGPU adapter on CI) so the WebGPU tests can acquire an adapter.
• No public API changes.
• Documentation and TypeScript definitions were updated to match those changes (none needed — no API changes)

PR and Code Checklist

• semantic-release commit messages
• Run npm run reformat to have correctly formatted code

Testing

Two regression tests, one per fix; both fail without the fixes:

WEBGPU=1 NO_WEBGL=1 npx vitest run \
  Sources/Rendering/WebGPU/ImageMapper/test/testImageMapperCameraProjection.js \
  Sources/Rendering/WebGPU/TextureManager/test/testImageDataTextureCacheInvalidation.js

• This change adds or fixes unit tests
• Tested environment:
  • vtk.js: master (07c3e9a)
  • OS: macOS 15
  • Browser: Chromium (Playwright, headless) and Chrome, Apple Metal adapter

[daker]

+1 it will fix MultiSliceImageMapper example

[sedghi]

if you run the example in main it will be for webgpu view

but in this branch will become