[shubham-kumar1-eightfold]

SUMMARY:

Screen reader fixes. Only the Snackbar change affects existing usages; the other two are opt-in.

• Select: with improvedA11y, the results live region clears when the list closes, so a stale "N matches found." is no longer read in browse mode, and the count is announced again on reopen. Without improvedA11y nothing changes.
• Snackbar: with several SnackbarContainers mounted, each snack renders once instead of once per container. The serve event is now cancelable, and the first container to receive it claims it.
• Avatar: new ariaHidden prop, named as on Icon and TextInput, to hide a decorative avatar (for example one next to the person's name). aria-hidden passed to Avatar was silently dropped.

GITHUB ISSUE (Open Source Contributors)

NA

JIRA TASK (Eightfold Employees Only):

https://eightfoldai.atlassian.net/browse/ENG-222073
https://eightfoldai.atlassian.net/browse/ENG-222080
https://eightfoldai.atlassian.net/browse/ENG-222081

CHANGE TYPE:

• Bugfix Pull Request
• Feature Pull Request

TEST COVERAGE:

• Tests for this change already exist
• I have added unittests for this change

TEST PLAN:

• New tests, each failing on 2.59.4: Select clears the live region when an improvedA11y list closes; Snackbar renders once with two containers; Avatar ariaHidden.
• yarn test: 231 suites pass.
• Browser check of a dialog with an improvedA11y Select, an Avatar and a snack: live region empty after the list closes; one snack; avatar hidden from the accessibility tree.
• Checked in a consuming app's dev environment with this build installed: on a page that mounts several SnackbarContainers a toast renders once; the improvedA11y Select's live region empties after the list closes; an ariaHidden avatar is ignored by the accessibility tree.