fix(close-button): add a default slot containing visually hidden text for close button

[cdransf]

fix(close-button): add accessible name support for default slot

Description

Added visually hidden default slot rendering to sp-close-button so text content is accessible to screen readers while remaining invisible to sighted users.

Changes:

• Render default slot with .visually-hidden styling in CloseButton.ts
• Add .visually-hidden CSS class to close-button-overrides.css
• Add accessibility tests to verify screen reader support

Motivation and context

<sp-close-button>Close</sp-close-button> had no accessible name for screen readers because the default slot wasn't being rendered. This caused WCAG 4.1.2 (Name, Role, Value - Level A) violations when using slot content instead of the label attribute.

The label attribute already worked correctly (via aria-label), but the documented default slot pattern was inaccessible.

Related issue(s)

• fixes SWC-1150

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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.

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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

• Verify accessible name with default slot

  1. Go to close-button documentation
  2. Enable a screen reader (NVDA, JAWS, VoiceOver, etc.)
  3. Navigate to <sp-close-button>Close</sp-close-button> examples
  4. Expect screen reader announces "Close" as the button's accessible name

• Verify disabled state accessibility

  1. Navigate to disabled close button: <sp-close-button disabled>Disabled</sp-close-button>
  2. Expect screen reader announces "Disabled" and disabled state

• Verify label attribute still works

  1. Navigate to <sp-close-button label="Close"></sp-close-button>
  2. Expect screen reader announces "Close" via aria-label (existing behavior)

Device review

• Did it pass in Desktop?
• Did it pass in (emulated) Mobile?
• Did it pass in (emulated) iPad?

[changeset-bot]

⚠️ No Changeset found

Latest commit: b13b306

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[github-actions]

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