Release @astrojs/starlight@0.23.0 · withastro/starlight

#1846 2de67039 Thanks @delucis! - Updates @astrojs/mdx to v3 and enables MDX optimization by default

⚠️ Potentially breaking change: MDX optimization speeds up builds (Starlight’s docs are building ~40% faster for example), but restricts some advanced MDX features. See full details in the MDX optimization documentation.

Most Starlight users should be unaffected, but if you are using MDX files outside of Starlight pages with the components prop, you may see issues. You can disable optimization by adding MDX manually to your integrations array in astro.config.mjs:
```
import { defineConfig } from 'astro/config';
+ import mdx from '@astrojs/mdx';
import starlight from '@astrojs/starlight';

// https://astro.build/config
export default defineConfig({
	integrations: [
		starlight({
			title: 'My docs',
			// ...
		}),
+		mdx(),
	],
});
```
#1735 1a9ab50d Thanks @HiDeoo! - Adds custom styles for <details> and <summary> elements in Markdown content.
#1846 2de67039 Thanks @delucis! - ⚠️ BREAKING CHANGE: The minimum supported version of Astro is now 4.8.6

Please update Astro and Starlight together:
```
npx @astrojs/upgrade
```

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