fix: keep mobile sidebar open for portaled focus

[hkfoster]

Fixes #604

Summary

Fixes the mobile Sidebar closing unexpectedly when focus moves outside the sidebar into portaled interactive content, such as dropdown menus or popovers rendered from inside the sidebar.

The mobile Sidebar now closes on explicit dismissal actions only:

• Escape key
• Backdrop click

Changes

• Removed the mobile Sidebar focusout listener that closed the drawer when focus moved outside the sidebar DOM subtree.
• Updated the mobile Sidebar regression test to verify the drawer stays open when focus moves outside, matching portaled nested interactive behavior.
• Added a patch changeset for @cloudflare/kumo.

Validation

• pnpm --filter @cloudflare/kumo test:unit src/components/sidebar/sidebar.test.tsx

• pnpm --filter @cloudflare/kumo typecheck

• pnpm --filter @cloudflare/kumo lint

• Reviews

  • bonk has reviewed the change
  • automated review not possible because: targeted behavioral fix for mobile focus handling

• Tests

  • Tests included/updated
  • Automated tests not possible - manual testing has been completed as follows:
  • Additional testing not necessary because:

[pkg-pr-new]

npm i https://pkg.pr.new/@cloudflare/kumo@623

commit: fa53c79

[github-actions]

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Commit: fa53c79

[github-actions]

Visual Regression Report — 2 changed, 0 unchanged

2 screenshot(s) with visual changes:

Dialog (Open)

23,408,620 px (93.43%) changed

Before	After	Diff

Select (Open)

23,586,636 px (93.42%) changed

Before	After	Diff

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Generated by Kumo Visual Regression