test: land Vitest 5 with jest-dom matcher types

[enricopiovesan]

Summary

• Land the Vitest ^5.0.0 npm-major bump (and matching @vitest/coverage-v8) that Dependabot build(deps-dev): Bump the npm-major group across 1 directory with 2 updates #306 could not merge.
• Augment Vitest 5's two-parameter Matchers interface so Testing Library DOM matchers typecheck under tsc -b.
• Keep the existing @testing-library/jest-dom setup import (the /vitest entry cannot resolve vitest from the hoisted jest-dom package in this workspace layout).

Governing Spec

N/A — test-runner / types only. No architecture or runtime-contract change.

Project Item

land-vitest-5 (Project 2 PVTI_lADOEbiBt84BbzAzzg6FxKM)

Definition of Done

• All workspaces that pinned vitest ^4.1.11 are on vitest ^5.0.0 (and @vitest/coverage-v8 ^5.0.0)
• tsc -b recognizes Testing Library DOM matchers (no TS2339 on toBeInTheDocument / toBeDisabled)
• Existing unit tests still pass without rewriting product UI
• Dependabot PR build(deps-dev): Bump the npm-major group across 1 directory with 2 updates #306 commented and closed as superseded (follow-up in this PR)
• Production-baseline embed/sync/SDK items N/A (test-runner / types only)

Validation

• npm run typecheck
• npm run lint
• npm run test
• bash scripts/ci/repository_checks.sh

Made with Cursor