withastro/astro ? reverse-engineered prompt

Build me a modern web framework that is specifically designed for content-driven websites like blogs, marketing sites, and portfolios. The main focus should be on performance, generating extremely fast and lightweight static sites by default.

A core feature is that it should be framework-agnostic, allowing developers to use their favorite UI components from React, Vue, Svelte, and others, side-by-side in the same project. The idea is to ship zero JavaScript by default, but let developers "hydrate" individual interactive components as needed — like "islands of interactivity."

It should be a complete toolkit, including a command-line tool to easily start new projects from templates. Please also include a system for official integrations to handle common tasks like generating sitemaps, creating RSS feeds, and deploying to popular hosting platforms like Vercel and Netlify.