Amélioration configuration Docusaurus et implémentation i18n

- Add language switcher to navbar for bilingual site (FR/EN)
- Remove intro page, use presentation as entry point
- Add example pages to all documentation categories
- Configure categories with generated-index for page listings
- Update footer and homepage links to reference presentation
- Enhance configuration with best practices:
  - Add metadata and SEO keywords
  - Enable RSS/Atom feeds for blog
  - Configure sitemap generation
  - Add syntax highlighting for YAML, HCL, Docker
  - Enable Mermaid diagram support
  - Configure table of contents settings
  - Respect user color scheme preferences
  - Add last update metadata to docs
- Fix deprecated onBrokenMarkdownLinks configuration
- Create bilingual example pages with practical code examples
- Update all i18n translations for consistency

This update brings the site in line with Docusaurus 3.x best practices
and provides a solid foundation for documentation growth.

src/pages/index.tsx

@@ -19,7 +19,7 @@ function HomepageHeader() {
         <div className={styles.buttons}>
           <Link
             className="button button--secondary button--lg"
-            to="/docs/intro">
+            to="/docs/presentation">
             Découvrir la documentation
           </Link>
           <Link