fix: keep S2 toast controls spaced from the expanded list while scrol…

[Zakkaus]

When the expanded toast list overflows, its padding toward the Clear all / Collapse buttons scrolls away with the content and toasts sit flush against the buttons. This moves that spacing to the region so it stays constant while scrolling.

✅ Pull Request Checklist:

• Included link to corresponding React Spectrum GitHub Issue.
• Added/updated unit tests and storybook for this change (for new code or code which already has tests).
• Filled out test instructions.
• Updated documentation (if it already exists for this component).
• Looked at the Accessibility Practices for this feature - Aria Practices
• I understand every change in this PR and can explain why it's there.
• If AI-assisted, I followed our AI contribution guidance and pointed my assistant at CLAUDE.md.

📝 Test Instructions:

In the S2 Storybook Toast Example story, show about 12 toasts, click the stack to expand, and scroll. The gap between the buttons and the list no longer disappears.

🧢 Your Project:

[snowystinger]

Thanks for the PR.
Can you provide a before and after screenshot of what you mean? Usually this would have an Issue first with that information, that way we can confirm the issue and the fix.
(yes, I realise this one is fairly obvious, but it helps with historical context)

[snowystinger]

what happened to the 16, now they're both only 8

[Zakkaus]

Still 16 total on the viewport side: 8 on the list for the focus ring, 8 moved to the region so it stays outside the scroll container. The side next to the buttons goes from 8 to 16 for the same reason, and the buttons now keep 8 from the viewport edge.