update SelectPanel Multi Select Modal story

[llastflowers]

Update SelectPanel Multi Select Modal story to not update labels unless user saves changes in modal

Closeshttps://github.com/github/primer/issues/6131

Changelog

Changed

Changes made in SelectPanel Multi Select Modal variant are now no longer reflected in the background via labels until user saves changes in the modal. Canceling or clicking outside the modal will also discard any unsaved changes.

Rollout strategy

• Patch release
• Minor release
• Major release; if selected, include a written rollout or migration plan
• None; if selected, include a brief description as to why

Testing & Reviewing

Merge checklist

• Added/updated tests
• Added/updated documentation
• Added/updated previews (Storybook)
• Changes are SSR compatible
• Tested in Chrome
• Tested in Firefox
• Tested in Safari
• Tested in Edge
• (GitHub staff only) Integration tests pass at github/github (Learn more about how to run integration tests)

[changeset-bot]

🦋 Changeset detected

Latest commit: e5f2b35

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@primer/react	Patch

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[Copilot]

Pull request overview

This PR updates the MultiSelectModal story to implement deferred save behavior, where changes made within the modal are not reflected in the button label until the user explicitly clicks the Save button. Canceling or clicking outside the modal discards any unsaved changes.

Key Changes

• Added savedSelection state to track the committed/saved selection separately from the working selected state
• Updated button text to display savedSelection instead of the current selected items, preventing real-time updates while the modal is open
• Enhanced onOpenChange handler to only update savedSelection when the modal closes with gesture type 'selection' (Save button clicked)

[llastflowers]

Integration tests skipped; Storybook-only changes in this PR

[liuliu-dev]

❤️