chore(deps-dev): upgrade vitest to v5

[erunion]

Upgrade the test runner from Vitest 4 to Vitest 5. Migration notes: https://vitest.dev/guide/migration/

Changes

• Bump vitest and @vitest/coverage-v8 from ^4.1.9 to ^5.0.0
• Remove @vitest/expect — Vitest 5 bundles assertions into vitest itself, and the standalone package no longer shares state with Vitest's expect
• Update our custom toBeValidSchema matcher to augment Matchers<R, T> and import MatcherResult from vitest
• Ignore Vitest 5's new .vitest/ artifact directory in git, oxlint, and oxfmt
• Pin coverage.include to src — Vitest 5's coverageConfigDefaults.exclude is empty and include/exclude matching is stricter, which otherwise reports dist/ and test helpers
• Update snapshot keys for pretty-format title changes (interpolated strings are no longer quoted). createGHA cases now use an explicit $name instead of concatenating $cmd $label
• Harden GHA test mocks: fake timers are limited to Date, git.revparse is mocked, and prompts.inject / prompts.override are reset between tests

Compatibility notes

Vitest 5 requires Node.js >= 22.12.0 (and Vite >= 6.4.0, pulled in transitively). That only affects running tests; the published CLI engines remain >=20.10.0.

CI already exercises lts/-1 / lts/* / latest, which are all Node 22+.

clearMocks now defaults to true. Our spies are set up in beforeEach, so this should not change test behavior.

Verification

npx vitest run --coverage locally: 35 files passed, 606 tests passed (15 skipped, 11 todo). Coverage on src/ is ~89% statements.

  

[greptile-apps]

Confidence Score: 5/5

The PR appears safe to merge.

No blocking failure remains.

Important Files Changed

Filename	Overview
package.json	Upgrades the Vitest development dependencies and removes the obsolete standalone assertion dependency.
package-lock.json	Resolves Vitest 5 and its updated transitive test-toolchain dependencies.
vitest.config.ts	Limits coverage collection to source files while preserving the generated GitHub Actions bundle exclusion.
test/helpers/vitest.matchers.ts	Migrates the custom matcher typing and result import to Vitest 5’s bundled assertion API.
test/helpers/git-mock.ts	Adds the Git-root mock and strengthens cleanup of timers and global prompt state.
test/lib/createGHA.test.ts	Adjusts fake-timer and prompt setup to remain deterministic under Vitest 5.

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