v0.2.1

Docs navigation performance

• Strip MDX bodies from navigation passed to the client DocsShell
• Cache materialized entries per locale
• Hoist HeadingLinks into DocsShell (single mount per docs session)
• Code-split interactive MDX widgets (Mermaid, Tabs, Accordion)
• Stream DocsMdx behind Suspense with loading skeleton
• Export getCoreMdxComponents / getInteractiveMdxComponents / toNavItem

Closes #2