Remove support for sx from AvatarStack component

[llastflowers]

Closes https://github.com/github/primer/issues/5748

Current sx usage: 0

✅ Don't need to separately update github-ui components to use @primer/styled-react

Changelog

Removed

Remove support for sx from the AvatarStack component, and associated stories, docs, and tests

Rollout strategy

• Major release; if selected, include a written rollout or migration plan

This component currently has 0 sx usage in dotcom, and therefore does not need the @primer/styled-react wrapper. this will be confirmed again before merging.

Merge checklist

• Added/updated tests
• Added/updated documentation
• Added/updated previews (Storybook)
• Changes are SSR compatible
• Tested in Chrome
• Tested in Firefox
• Tested in Safari
• Tested in Edge
• (GitHub staff only) Integration tests pass at github/github (Learn more about how to run integration tests)

[changeset-bot]

🦋 Changeset detected

Latest commit: 15a017e

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

This PR includes changesets to release 2 packages

Name	Type
@primer/react	Major
@primer/styled-react	Major

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

[github-actions]

👋 Hi, this pull request contains changes to the source code that github/github depends on. If you are GitHub staff, we recommend testing these changes with github/github using the integration workflow. Thanks!

[github-actions]

size-limit report 📦

Path	Size
packages/react/dist/browser.esm.js	89.9 KB (-0.04% 🔽)
packages/react/dist/browser.umd.js	89.98 KB (-0.15% 🔽)

[Copilot]

Pull Request Overview

This PR removes the deprecated sx prop support from the AvatarStack component as part of migrating away from styled-components. The change is part of a larger effort to modernize the component API and eliminate dependencies on the legacy styling system.

Key changes:

• Removed sx prop from AvatarStack component interface and implementation
• Cleaned up related Storybook stories, documentation, and tests
• Added changeset for major version release

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
packages/react/src/AvatarStack/AvatarStack.tsx	Removed SxProp import, sx prop from type definition and component destructuring
packages/react/src/AvatarStack/AvatarStack.stories.tsx	Removed sx prop configuration from Storybook argTypes
packages/react/src/AvatarStack/AvatarStack.docs.json	Removed sx prop from component documentation
packages/react/src/AvatarStack/AvatarStack.dev.stories.tsx	Removed SxProp story example
e2e/components/AvatarStack.test.ts	Removed SX Prop test case from e2e test suite
.changeset/few-mails-sing.md	Added changeset entry for major version bump