refactor: update build config for @primer/styled-react to rolldown

[joshblack]

Closes #

N/A

Changelog

New

N/A

Changed

• Updated @primer/styled-react to build JavaScript with Rolldown and emit declarations with TypeScript.

Removed

• Removed the package Rollup build config and Rollup build dependencies.

Rollout strategy

• Patch release
• Minor release
• Major release; if selected, include a written rollout or migration plan
• None; build tooling-only change with no public runtime API change

Testing & Reviewing

Validated as part of the stack with npm run build, npm run type-check, npm run lint, npm run lint:css, npm run format:diff, and npm test -- --run.

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-ui (Learn more about how to run integration tests)

[github-actions]

⚠️ Action required

👋 Hi, this pull request contains changes to the source code that github/github-ui depends on. If you are GitHub staff, test these changes with github/github-ui using the integration workflow. If this doesn't work, you can also use the original workflow here. Check the integration testing docs for step-by-step instructions. Or, apply the integration-tests: skipped manually label to skip these checks.

To publish a canary release for integration testing, apply the Canary Release label to this PR.

[changeset-bot]

⚠️ No Changeset found

Latest commit: 7a8cdbb

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[primer]

🤖 Lint issues have been automatically fixed and committed to this PR.

[primer]

🤖 Lint issues have been automatically fixed and committed to this PR.

[Copilot]

Pull request overview

This PR refactors the @primer/styled-react package build pipeline to use Rolldown for JavaScript bundling while continuing to emit TypeScript declaration files via tsc, removing the older Rollup-based setup.

Changes:

• Switch packages/styled-react build script from Rollup to rolldown.
• Update the build config to use Rolldown-compatible plugins/config shape.
• Remove Rollup build dependencies and add the rolldown dependency (with corresponding lockfile updates).

Show a summary per file

File	Description
packages/styled-react/script/build	Updates the package build script to run rolldown before tsc and the components manifest generator.
packages/styled-react/rolldown.config.js	Migrates the bundler config to Rolldown and updates plugin wiring for Babel + directive preservation.
packages/styled-react/package.json	Removes Rollup-related devDependencies and adds rolldown.
package-lock.json	Reflects dependency graph changes from the Rollup → Rolldown migration.

Copilot's findings

Comments suppressed due to low confidence (2)

packages/styled-react/rolldown.config.js:2

• RolldownMagicString is typically provided by @rolldown/pluginutils rather than the main rolldown entrypoint. Importing it from rolldown risks a runtime config-load failure if that re-export isn’t present in the installed version.
  packages/styled-react/rolldown.config.js:102
• This hook mutates code (prepends the directive) but now always returns map: null. That drops sourcemap information compared to the previous implementation and can break debugging/stack traces when sourcemaps are enabled.

• Files reviewed: 3/4 changed files
• Comments generated: 0