chore: remove Box, BoxProps export

[francinelucca]

Part of https://github.com/github/primer/issues/5425

Changelog

New

• Box component in @primer/styled-react

Changed

• updated imports in @primer/styled-react to pull from local Box component

Removed

• exports for Box, BoxProps in @primer/react

Rollout strategy

• Patch release
• Minor release
• Major release; if selected, include a written rollout or migration plan
• None; if selected, include a brief description as to why

Testing & Reviewing

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: 7893bcc

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

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

[Copilot]

Pull Request Overview

This PR removes the Box and BoxProps exports from the main @primer/react package while maintaining backward compatibility in the legacy @primer/styled-react package by implementing a local styled-components-based Box component.

Key Changes:

• Removed Box and BoxProps from @primer/react package exports
• Implemented a standalone Box component in @primer/styled-react with deprecation warnings
• Updated all internal imports to use the local Box implementation

Reviewed Changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
packages/react/src/index.ts	Removed Box and BoxProps exports from main package
packages/styled-react/src/components/Box.tsx	Implemented local Box component with styled-system and deprecation warnings
packages/styled-react/src/components/RelativeTime.tsx	Updated to import Box from local components
packages/styled-react/src/components/RadioGroup.tsx	Updated to import Box from local components
packages/styled-react/src/components/NavList.tsx	Updated to import Box from local components
packages/styled-react/src/components/CheckboxGroup.tsx	Updated to import Box from local components
packages/react/src/tests/snapshots/exports.test.ts.snap	Updated snapshot to reflect removed exports
packages/react/src/tests/ThemeProvider.test.tsx	Updated test to import Box from local module

[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!

[primer-integration]

👋 Hi from github/github-ui! Your integration PR is ready: https://github.com/github/github-ui/pull/4724

[jonrohan]

[primer-integration]

🟢 ci completed with status success.

[github-actions]

👋 Hi, there are new commits since the last successful integration test. We recommend running the integration workflow once more, unless you are sure the new changes do not affect github/github. Thanks!