Claude/pr 389 type issue vtky29 - #391

apps/react's test setup imported the root `@testing-library/jest-dom`
entry, which only pulls in `types/jest.d.ts` — that file augments the
global `jest.Matchers` interface, not vitest's `Assertion`.
This worked by accident: vitest 4 declared a global `jest` namespace and
chained its assertions through it (`@vitest/expect`:
`interface JestAssertion<T> extends jest.Matchers<void, T>`), so the
jest-only augmentation leaked into `expect`. vitest 5 removes that
bridge — `JestAssertion<R, T>` now extends `CustomMatcher<R>` and no
`jest` namespace is shipped — leaving every jest-dom matcher untyped
(56 TS2339 errors across the app's test files).
Import `@testing-library/jest-dom/vitest` instead, which augments the
`vitest` module directly. This is what apps/next.js already does, so the
three apps using jest-dom now share one convention.
The change is valid on both majors, so it lands independently of the
vitest 5 bump: full check-types + test + lint pass on vitest 4.1.11
(20/20) and on vitest 5.0.0 (20/20, 88 react tests green).
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01U8NHR2C6Fd82H1XBBme51p