Addon Themes: Define missing React dependencies

[ghengeveld]

Closes #31651

What I did

Added missing react and react-dom to devDependencies for addon-themes, similar to other addons.

Checklist for Contributors

Testing

The changes in this PR are covered in the following automated tests:

• stories
• unit tests
• integration tests
• end-to-end tests

Manual testing

This section is mandatory for all contributions. If you believe no manual test is necessary, please state so explicitly. Thanks!

Documentation

• Add or update documentation reflecting your changes
• If you are deprecating/removing a feature, make sure to update
  MIGRATION.MD

Checklist for Maintainers

• When this PR is ready for testing, make sure to add ci:normal, ci:merged or ci:daily GH label to it to run a specific set of sandboxes. The particular set of sandboxes can be found in code/lib/cli-storybook/src/sandbox-templates.ts

• Make sure this PR contains one of the labels below:

  Available labels

  • bug: Internal changes that fixes incorrect behavior.
  • maintenance: User-facing maintenance tasks.
  • dependencies: Upgrading (sometimes downgrading) dependencies.
  • build: Internal-facing build tooling & test updates. Will not show up in release changelog.
  • cleanup: Minor cleanup style change. Will not show up in release changelog.
  • documentation: Documentation only changes. Will not show up in release changelog.
  • feature request: Introducing a new feature.
  • BREAKING CHANGE: Changes that break compatibility in some way with current major version.
  • other: Changes that don't fit in the above categories.

🦋 Canary release

This PR does not have a canary release associated. You can request a canary release of this pull request by mentioning the @storybookjs/core team here.

core team members can create a canary release here or locally with gh workflow run --repo storybookjs/storybook canary-release-pr.yml --field pr=<PR_NUMBER>

Greptile Summary

Updates @storybook/addon-themes to properly declare React build dependencies by adding missing React packages as devDependencies.

• Adds react and react-dom to devDependencies in code/addons/themes/package.json for build-time dependencies
• Fixes build failures in non-React projects (e.g., Svelte) that were encountering "Could not resolve 'react'" errors
• Aligns with other Storybook addons' dependency management practices by keeping React as a dev-only dependency

[greptile-apps]

LGTM

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[nx-cloud]

View your CI Pipeline Execution ↗ for commit e9bfa24.

Command	Status	Duration	Result
nx run-many -t check -c production --parallel=7	✅ Succeeded	1s	View ↗
nx run-many -t build -c production --parallel=3	✅ Succeeded	2s	View ↗

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☁️ Nx Cloud last updated this comment at 2025-06-07 07:22:09 UTC

[storybook-app-bot]

Package Benchmarks

^{Commit: e9bfa24, ran on 7 June 2025 at 07:28:34 UTC}

The following packages have significant changes to their size or dependencies:

@storybook/cli

	Before	After	Difference
Dependency count	324	324	0
Self size	244 KB	244 KB	0 B
Dependency size	97.79 MB	97.83 MB	🚨 +43 KB 🚨
Bundle Size Analyzer	Link	Link

@storybook/codemod

	Before	After	Difference
Dependency count	267	267	0
Self size	31 KB	31 KB	0 B
Dependency size	82.19 MB	82.23 MB	🚨 +43 KB 🚨
Bundle Size Analyzer	Link	Link

[greptile-apps]

LGTM

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