chat: pin product quality in persistent progress tests #336700

Fixes microsoft/vscode-engineering#3894.

Summary

The persistent-progress renderer test asserts the Stable product-icon CSS class, but its fixture inherits the ambient build's product quality. On Insiders CI the renderer correctly produces the Insiders class, so the test fails identically across platforms.

Pin IProductService.quality to stable in createPersistentProgressRenderer, preserving the remaining product-service properties and all existing assertions. This is a test-only change; production rendering is unchanged.

This is an alternative to #336693. It omits the redundant _serviceBrand: undefined before the typed product-service spread, avoiding the TS2783 error in that draft.

Validation

• Reproduced the original assertion failure by changing only the local product quality to insider.


• 
  npm run gulp compile-client — passed with 0 errors.


• 
  node build/hygiene.ts src/vs/workbench/contrib/chat/test/browser/widget/chatListRenderer.test.ts — passed; commit hygiene hook also passed.


• Related Electron suites (chatListRenderer, chatIcons, and chatWorkingLogo) on macOS — 424 passing, 1 pre-existing skipped, both with normal OSS product quality and with quality: 'insider'.

./scripts/test.sh \

  --run src/vs/workbench/contrib/chat/test/browser/widget/chatListRenderer.test.ts \

  --run src/vs/workbench/contrib/chat/test/browser/chatIcons.test.ts \

  --run src/vs/workbench/contrib/chat/test/browser/widget/chatWorkingLogo.test.ts \

  --reporter dot

The temporary product-quality override used for validation is not included in this PR.