docs: Manage system color scheme changes (#6627)

This PR introduces persistance between system color theme and user
selected color theme.

Before:


https://github.com/user-attachments/assets/94a00142-b3fd-4b5e-8e29-f1bdb69363d7


After:


https://github.com/user-attachments/assets/b36cb663-b322-4eff-a507-6f6d8a3264cc

packages/docs-reanimated/docusaurus.config.js

@@ -78,6 +78,9 @@ const config = {
     /** @type {import('@docusaurus/preset-classic').ThemeConfig} */
     ({
       image: 'img/og-image.png',
+      colorMode: {
+        respectPrefersColorScheme: true,
+      },
       metadata: [
         { name: 'og:image:width', content: '1200' },
         { name: 'og:image:height', content: '630' },