docs: add storybook plugins (barebones)

[castastrophe]

Description

This PR adds essential Storybook plugins to the second-generation Spectrum Web Components package to enhance the development and documentation experience. The changes include adding three key Storybook addons: docs, accessibility (a11y), and designs, along with configuration updates to enable auto-documentation and centered layout.

Motivation and context

The second-generation SWC package was missing essential Storybook plugins that are crucial for:

• Documentation: Auto-generated docs from component stories
• Accessibility: Built-in a11y testing and reporting
• Design integration: Support for design system integration and Figma links

These plugins are standard in modern component development workflows and will improve the developer experience for contributors working on the second-generation components.

Related issue(s)

• SWC-1245

Author's checklist

• I have read the CONTRIBUTING and PULL_REQUESTS documents.
• I have reviewed at the Accessibility Practices for this feature, see: Aria Practices
• I have added automated tests to cover my changes.
• I have included a well-written changeset if my change needs to be published.
• I have included updated documentation if my change required it.

Reviewer's checklist

• Includes a Github Issue with appropriate flag or Jira ticket number without a link
• Includes thoughtfully written changeset if changes suggested include patch, minor, or major features
• Automated tests cover all use cases and follow best practices for writing
• Validated on all supported browsers
• All VRTs are approved before the author can update Golden Hash

Manual review test cases

• Storybook addons functionality

  1. Go to second-gen/packages/swc/ directory
  2. Run yarn storybook to start the Storybook development server
  3. Expect to see Docs, Accessibility, and Design tabs in the Storybook interface

• Auto-documentation generation

  1. Navigate to any component story in Storybook
  2. Check the Docs tab
  3. Expect to see auto-generated documentation with component props and examples

• Accessibility testing

  1. Open any component story in Storybook
  2. Navigate to the Accessibility tab
  3. Expect to see accessibility violations and recommendations

[changeset-bot]

⚠️ No Changeset found

Latest commit: d7025fb

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

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[castastrophe]

This wasn't actually being used in this file so the import wasn't needed.

[castastrophe]

I think centered or padded are nice customer experiences. The downside of making every component fullscreen is that the smaller components get squashed into the top left corner.

[castastrophe]

Automatically triggers documentation pages for every component. Components can opt-out using tags: ['!autodocs']

[github-actions]

📚 Branch Preview

• Documentation Site
• Storybook

🔍 Visual Regression Test Results

When a visual regression test fails (or has previously failed while working on this branch), its results can be found in the following URLs:

• Spectrum | Light | Medium | LTR
• Spectrum | Dark | Large | RTL
• Express | Light | Medium | LTR
• Express | Dark | Large | RTL
• Spectrum-two | Light | Medium | LTR
• Spectrum-two | Dark | Large | RTL
• High Contrast Mode | Medium | LTR

Deployed to Azure Blob Storage: pr-5737

If the changes are expected, update the current_golden_images_cache hash in the circleci config to accept the new images. Instructions are included in that file.
If the changes are unexpected, you can investigate the cause of the differences and update the code accordingly.

[castastrophe]

This lets us bring over the Figma resources that we have linked in CSS.

[github-actions]

Tachometer results

Currently, no packages are changed by this PR...