SCC-5375: MultiSelect performance

[KaseyW31]

Fixes JIRA ticket SCC-5375

This PR does the following:

• In the MultiSelect component, memoizes Checkboxes to prevent rerendering of all list items on single input
• Adds callbacks in useMultiSelect

How has this been tested?

• Local build of storybook - verify that only checkboxes that are selected/deselected are rerendered

Accessibility concerns or updates

Accessibility Checklist

• Checked Storybook's "Accessibility" tab for color contrast and other issues.
• The feature works with keyboard inputs including tabbing back and forward and pressing space, enter, arrow, and esc keys.
• For hidden text or when aria-live is used, a screenreader was used to verify the text is read.
• For features that involve UI updates and focusing on DOM refs, focus management was reviewed.
• The feature works when the page is zoomed in to 200% and 400%.

Open Questions

Checklist:

• I have updated the Storybook documentation and changelog accordingly.
• I have added relevant accessibility documentation for this pull request.
• All new and existing tests passed.

Front End Review:

• Review the Vercel preview deployment once it is ready.

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Project	Deployment	Actions	Updated (UTC)
nypl-design-system	Ready	Preview, Comment	Jul 7, 2026 6:16pm

[7emansell]

heads up @bigfishdesign13 @EdwinGuzman published an rc to test this out

[KaseyW31]

Closing because these changes seem to slightly hinder performance when the MultiSelect component is repeatedly rerendered (I'm suspecting because of a higher memory overhead upon first render), which may affect oher consuming apps. Trying a new approach with a lazy loading option instead here