@reach/portal: Support Remounting in <Activity>

[WITS]

This ensures that the portalNode ref is reset to null when removing the portalNode element from the DOM. Without this the <Portal> doesn't properly re-add a node to the DOM when it's remounted inside of React's <Activity> component.

Next.js 16's Cache Components use <Activity> to restore UI when navigating back via history, so without this change navigating backwards in history can break portals.

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[changeset-bot]

🦋 Changeset detected

Latest commit: 87bf502

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

This PR includes changesets to release 25 packages

Name	Type
@reach/portal	Patch
@reach/combobox	Patch
@reach/dialog	Patch
@reach/popover	Patch
@reach/tooltip	Patch
reach-storybook	Patch
@reach/alert-dialog	Patch
@reach/dropdown	Patch
@reach/listbox	Patch
@reach/menu-button	Patch
@reach/accordion	Patch
@reach/alert	Patch
@reach/auto-id	Patch
@reach/checkbox	Patch
@reach/descendants	Patch
@reach/disclosure	Patch
@reach/machine	Patch
@reach/polymorphic	Patch
@reach/rect	Patch
@reach/skip-nav	Patch
@reach/slider	Patch
@reach/tabs	Patch
@reach/utils	Patch
@reach/visually-hidden	Patch
@reach/window-size	Patch

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