feat: add React Compiler support for Heading, Link, Pagehead, Portal, and SideNav

[joshblack]

Closes N/A

Changelog

New

N/A

Changed

• Enabled React Compiler support for Heading, Link, Pagehead, Portal, and SideNav.
• Added a patch changeset for the rendering performance improvement.

Removed

N/A

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

• npx eslint --no-cache packages/react/src/Heading/**/*.{ts,tsx} packages/react/src/Link/**/*.{ts,tsx} packages/react/src/Pagehead/**/*.{ts,tsx} packages/react/src/Portal/**/*.{ts,tsx} packages/react/src/SideNav.tsx packages/react/src/__tests__/SideNav*.tsx
• npm test -- --run packages/react/src/Heading packages/react/src/Link packages/react/src/Pagehead packages/react/src/Portal packages/react/src/__tests__/SideNav.test.tsx packages/react/src/__tests__/SideNav.types.test.tsx
• npm run build && npm test -- --run && npm run type-check && npm run lint && npm run lint:css && npm run format:diff
• Storybook started and responded locally at http://localhost:6006.

Merge checklist

• Added/updated tests (not needed; existing coverage validated)
• Added/updated documentation (not needed)
• Added/updated previews (not needed)
• 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)

[changeset-bot]

🦋 Changeset detected

Latest commit: 7284933

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

This PR includes changesets to release 1 package

Name	Type
@primer/react	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

[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.

[Copilot]

Pull request overview

Enables React Compiler support for additional @primer/react components by removing them from the opt-out list, and records the user-visible performance improvement via a patch changeset.

Changes:

• Removed Heading, Link, Pagehead, Portal, and SideNav from the React Compiler “unsupported” ignore patterns.
• Added a patch changeset describing the resulting rendering performance improvement.

Show a summary per file

File	Description
packages/react/script/react-compiler.mjs	Updates the React Compiler exclusion list to allow compilation for Heading/Link/Pagehead/Portal/SideNav.
.changeset/react-compiler-primitives.md	Adds a patch changeset entry for the performance improvement.

Copilot's findings

• Files reviewed: 2/2 changed files
• Comments generated: 1