Docs: show the new icon set in the landing list and admin screenshots

[SandObserver]

Summary

• Replace the Now Playing row icon and the drag handles in the landing page's Settings list with the icon set's glyphs.
• Recapture the Appearance, Badge and Labels admin screenshots in light and dark, under new hashed names, and remove the six old files.
• Sync the admin scripts for the label reorder arrows.

Testing
npm run build and npm run check pass. Screenshots captured in Chromium at 1280 wide, device scale 2, light and dark; the landing list checked in Chrome.

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:	ab956af
Status:	✅  Deploy successful!
Preview URL:	https://6143ff82.stackyard-docs.pages.dev
Branch Preview URL:	https://docs-new-icons-landing-shots.stackyard-docs.pages.dev

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