feat: add @chromatic-com/vitest, minimal setup

[AriPerkkio]

Issue: Related to #295

What Changed

The most minimal implementation required for generating snapshot and archives on file system during test run. Not configurable, controllable or extensible.

How to test

$ cd <project-root>
$ yarn test:unit
$ yarn test:vitest
$ yarn archive-storybook:vitest

Preview release

• @chromatic-com/vitest@0.0.1-ed4418f-20260330072141

https://github.com/chromaui/chromatic-e2e/actions/runs/23732773313/job/69130090147

[changeset-bot]

🦋 Changeset detected

Latest commit: 40f6802

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 2 packages

Name	Type
@chromatic-com/shared-e2e	Patch
@chromatic-com/vitest	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[codecov]

Codecov Report

❌ Patch coverage is 82.52427% with 18 lines in your changes missing coverage. Please review.
✅ Project coverage is 93.02%. Comparing base (202b83d) to head (40f6802).
⚠️ Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
packages/vitest/src/browser/public/takeSnapshot.ts	57.14%	11 Missing and 1 partial ⚠️
packages/vitest/src/node/commands.ts	93.87%	3 Missing ⚠️
packages/vitest/src/node/plugin.ts	88.88%	2 Missing ⚠️
packages/vitest/src/browser/getCurrentTest.ts	85.71%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #296      +/-   ##
==========================================
- Coverage   95.75%   93.02%   -2.73%     
==========================================
  Files          14       19       +5     
  Lines         400      502     +102     
  Branches       68       86      +18     
==========================================
+ Hits          383      467      +84     
- Misses         16       33      +17     
- Partials        1        2       +1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[mrmckeb]

Really excited to test this one out!