Improve Getting Started experience

[techniq]

• [x] Setup npm create svelte-ux@latest
  • Templates
    • [x] Minimal / Barebones
    • [x] Starter (with AppLayout / navigation)
    • [x] with LayerChart
• [x] Support opening in
  • [x] StackBlitz
    • https://developer.stackblitz.com/guides/integration/open-from-github
    • https://developer.stackblitz.com/guides/integration/create-with-sdk
  • [x] SvelteLab
  • [x] CodeSandbox
  • [ ] Standard REPL (if possible)
• [x] Add to README
• [ ] Update documentation
  • Add npm create svelte-ux@latest
  • Add link to Tailwind official docs
  • Add link to svelte-add
  • Add links to SvelteLab, StackBlitz, and CodeSandbox like on README
• [ ] Copy README.md to packages/svelte-ux/README.md from project root
• [ ] Improve package.json name when used on StackBlitz, etc

[techniq]

See also: @jycouet's REPL