Refresh homepage and download experience

[guanzhousongmicrosoft]

Summary

• redesign the homepage with tighter product messaging, clearer CTAs, and cleaner community/trust sections
• refresh the Download page into a clearer Docker vs Linux packages flow with a package finder and better next-step guidance
• add docs/install routing improvements for Docker and Linux packages
• fix GitHub Pages base-path handling so the site renders correctly under the repository URL

What changed

• updated homepage copy, layout, contributor section, and final CTA
• changed navbar terminology from Packages to Download
• improved /packages with verified Linux package targets, internal docs links, and onboarding links for Python, Node.js, and VS Code
• added shared command snippet UI for copyable install commands
• added /docs/getting-started/docker and /docs/getting-started/packages support in the docs flow
• fixed static asset and route prefixes for GitHub Pages deployments