feat: switch to multi-page layout

[Th3S4mur41]

Closes #1101

[Copilot]

Pull Request Overview

This PR implements a switch to a multi-page layout with internationalization, splitting content into separate MDX pages for different languages while updating navigation and configuration accordingly.

• New MDX pages have been added for English, French, Spanish, and German versions of the site (index, photos, videos, contact, and about pages).
• The Navigation component has been updated to use URL paths instead of hash anchors, and the Astro config now includes i18n and MDX settings.
• Dependencies and configuration files (package.json and astro.config.mjs) have been updated to support the new layout.

Reviewed Changes

Copilot reviewed 33 out of 33 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/content/pages/index.mdx	Introduced main page content with images and MDX structure.
src/content/pages/fr/*.mdx	Added French pages for videos, photos, index, and contact content.
src/content/pages/es/*.mdx	Added Spanish pages for videos, photos, index, and contact content.
src/content/pages/de/*.mdx	Added German pages for videos, photos, index, and contact content.
src/content/pages/about.mdx	Added about page content.
src/content.config.ts	Configured MDX collection for pages.
src/components/Navigation.astro	Updated navigation links for multi-page routing.
src/components/LazyYouTube.astro	Added a lazy-loading YouTube component with inline styles and logic.
package.json	Added dependency for MDX support.
astro.config.mjs	Added i18n configuration and MDX integration.