[Frontend] Create the Astro-based frontend

[alikia2x]

Objective

Create an Astro+React+UnoCSS project under apps/web, which includes some simple pages and dynamically renders and returns the webpage on the server side.

Acceptance Criteria

• Homepage / shows a simple message
• /song/:id/info shows some basic information of given song
• Astro, React, UnoCSS, server-side data fetching and rendering all set up