Docs: sync the bundled widget and dashboard code

[SandObserver]

Summary
Refresh the committed copies of the application widget and dashboard code from the app repository, via npm run sync-widgets.

• Update public/widgets/books/ for the medium and large sizes and the shelves config group.
• Update the remaining widget markup: backup, connections, dashboard-switch, disk-health, dns, github, nowplaying, system-summary, weather.
• Add public/js/widget-error.js and update the bundled dashboard, admin and toolbox modules that the previews load.

No prose changes. The Books page, the troubleshooting message table and the first-setup welcome text already describe this behaviour, and the Books preview stubs already carry the shelves shape.

Testing
npm run build and npm run check both pass. No prose or layout changes; the previews were not opened in a browser.

Checklist

• npm run build and npm run check both pass.
• Product UI is shown by running or capturing it, never recreated in CSS.
• Any new preview or screenshot carries no private hostnames or real data.
• Visual changes verified in both colour schemes and both docs themes.
• Links to the app repo still resolve.

[cloudflare-workers-and-pages]

Deploying stackyard-docs with    Cloudflare Pages

Latest commit:	3017c3a
Status:	✅  Deploy successful!
Preview URL:	https://9926d94c.stackyard-docs.pages.dev
Branch Preview URL:	https://docs-sync-widget-code-1-10-0.stackyard-docs.pages.dev

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