chore: report React Compiler migration errors

[joshblack]

Updates a column to our react compiler migration helper that reports on the error. You can see the result here in the job summary: https://github.com/primer/react/actions/runs/28247127773

Changelog

New

• Adds compiler error reasons to the React Compiler migration status report for files that are not migrated.

Changed

• Updates the migration status script to run React Compiler diagnostics with panicThreshold: 'all_errors' and collect logger.logEvent output per file.

Removed

• N/A

Rollout strategy

• Patch release
• Minor release
• Major release; if selected, include a written rollout or migration plan
• None; this only changes an internal reporting script and does not affect the published package.

Testing & Reviewing

• node script/react-compiler-migration-status.mts
• npx eslint --fix script/react-compiler-migration-status.mts
• npm run type-check

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)

[changeset-bot]

⚠️ No Changeset found

Latest commit: e480375

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[Copilot]

Pull request overview

Adds React Compiler diagnostic context to the migration status report so the GitHub Actions job summary shows why each “not migrated” file is failing/skipped, making the report more actionable for ongoing migration work.

Changes:

• Runs per-file Babel transforms with babel-plugin-react-compiler configured with panicThreshold: 'all_errors'.
• Captures React Compiler logger.logEvent output (plus CompilerError.details when thrown) and renders a new “Compiler errors” column for not-migrated files.
• Refactors output to a small write() helper and adds formatting/escaping for Markdown table cells.

Show a summary per file

File	Description
script/react-compiler-migration-status.mts	Adds React Compiler diagnostics and includes per-file error/skip reasons in the generated migration status report.

Review details

• Files reviewed: 1/1 changed files
• Comments generated: 0
• Review effort level: Low