Closes #31413, #31417

What I did

Fixed panel content to be consistent with spec.
Fixed exported parameter types to use new updated types.
Added rule IDs and severity badges to report.

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

Here's my summary of the key changes in this pull request:

Enhanced the A11y addon with improved UI consistency and accessibility reporting features, focusing on better test state handling and clearer violation reporting.

• Added severity badges (minor, moderate, serious, critical) and rule IDs in Report.tsx for better visual hierarchy
• Improved disabled state handling with clear parameter-based messaging in A11YPanel.tsx
• Added proper ARIA attributes for expandable sections and enhanced test state feedback
• Enhanced error handling with specific messages for different test states
• Updated typography and styling to maintain consistency with Storybook's theme system

The changes improve both the functionality and usability of the accessibility testing features while maintaining proper TypeScript typing and component organization.