fix(core): add playground wrapper and defaults for LayoutHeader docsite preview

[Geervan]

Summary

Fixes #5896

Adds default children and a Layout playground wrapper to LayoutHeader.doc.mjs so the component renders a visible header preview on the docsite Properties tab.

Problem

Navigating to the Properties tab for LayoutHeader on the docsite displayed an empty preview stage because LayoutHeader had no default child text and no parent Layout scaffold declared in its .doc.mjs metadata.

Solution

• Configured playground.defaults with children: 'Page Title' and hasDivider: true in packages/core/src/Layout/LayoutHeader.doc.mjs.
• Configured playground.wrapper with { component: 'Layout' }.
• Added unit test assertion in apps/docsite/src/__tests__/data-extraction.test.ts.
• Included patch changeset file .changeset/layout-header-playground-wrapper.md.

Acceptance Criteria Verification

• Add representative header content and a minimal Layout playground wrapper.
• The preview renders a visible header on first load.
• A relevant header control such as divider or height produces an observable update.
• Add focused preview/data-extraction coverage.

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Project	Deployment	Actions	Updated
astryx	Ready	Preview	Sep 2, 2026 1:35pm UTC

[github-actions]

PR Analysis Report

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Modified Components

Layout _{(@astryxdesign/core)} · View in Storybook

Metric	Before	After	Delta
Bundle Size (ESM)	N/A	N/A	N/A
Lines of Code	N/A	1481	-
Complexity	N/A	Very High (84)	-

Bundle Size Summary

Package	Size (ESM)	Size (CJS)	Gzipped
@astryxdesign/core	N/A	4.8KB	1.2KB

Accessibility Audit

Status: No accessibility violations detected.

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[cixzhang]

Thanks, this fixes the empty Properties preview. I verified the exact head renders “Page Title” inside Layout and the divider control updates visibly.

[Reviewed by Robohands]