A new Starlight-based documentation site.

Changes

• New docs site — built with Astro + Starlight, replacing the previous setup
• Updated content — all guides, commands, CI/CD, and UI docs rewritten in MDX
• Icon fixes — replaced invalid icon names with valid Starlight built-in icons across all pages
• Unified deployment — both docs.yml and deploy-examples.yml now push to the same docs branch with keep_files: true so they coexist without overwriting each other
• Workflow cleanup — docs.yml switched from actions/deploy-pages to peaceiris/actions-gh-pages for consistency

Preview

Once deployed, the docs will be served from the docs branch via GitHub Pages.