chore: Enhance documentation

[lanesawyer]

What

Enhances the documentation by:

• Modifying the calls to action to land them on the getting started page as the primary action, and examples as secondary
• Added vis-scatterbrain to the list of packages and as a full page in the Packages section
• Made an Astro component that uses Starlight to provide bash commands for npm, pnpm, and yarn in a resuable manner
• Enhanced the Packages pages to have install instructions, links to the examples, and then the under construction sign
• Updated the "Developers" section to read "Vis Package Developers" to make it more clear that it's info for people working on vis, not using it

How

Modified the pages
Used Starlight components
Made an Astro component that wraps up the package manager stuff into some tabs

Screenshots

PR Checklist

• Is your PR title following our conventional commit naming recommendations?
• Have you filled in the PR Description Template?
• Is your branch up to date with the latest in main?
• Do the CI checks pass successfully?
• Have you smoke tested the example applications?
• Did you check that the changes meet accessibility standards?
• Have you tested the application on these browsers?
  • Chrome (Fully supported)
  • Firefox (Major bug fixes supported)
  • Safari (Major bug fixes supported)