相比于其他框架，Astro 为什么特别强调 Theme？

Astro 对标的不是 React or Vue，而是 Next.js 之类的吧

这种框架的特点和原理是什么？

Astro is an all-in-one web framework for building fast, content-focused websites.

Key Features ​

• Component Islands: A new web architecture for building faster websites.
• Server-first API design: Move expensive hydration off of your users’ devices.
• Zero JS, by default: No JavaScript runtime overhead to slow you down.
• Edge-ready: Deploy anywhere, even a global edge runtime like Deno or Cloudflare.
• Customizable: Tailwind, MDX, and 100+ other integrations to choose from.
• UI-agnostic: Supports React, Preact, Svelte, Vue, Solid, Lit and more.

pnpm 又是个什么东西？