Update sitemaps and improve language handling

- Updated last modification dates in static and tools sitemaps to 2026-04-01.
- Enhanced language switching in the Header component to ensure language resources are loaded before changing the language.
- Added language resource loading logic in i18n configuration to support dynamic loading of language files.
- Improved SEO route page to ensure correct language is set based on URL parameters.
- Adjusted global CSS for deferred sections to optimize rendering.
- Configured Nginx to enable Brotli compression for better performance.

frontend/public/sitemap.xml

@@ -2,18 +2,18 @@
 <sitemapindex xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
   <sitemap>
     <loc>https://dociva.io/sitemaps/static.xml</loc>
-    <lastmod>2026-03-30</lastmod>
+    <lastmod>2026-04-01</lastmod>
   </sitemap>
   <sitemap>
     <loc>https://dociva.io/sitemaps/blog.xml</loc>
-    <lastmod>2026-03-30</lastmod>
+    <lastmod>2026-04-01</lastmod>
   </sitemap>
   <sitemap>
     <loc>https://dociva.io/sitemaps/tools.xml</loc>
-    <lastmod>2026-03-30</lastmod>
+    <lastmod>2026-04-01</lastmod>
   </sitemap>
   <sitemap>
     <loc>https://dociva.io/sitemaps/seo.xml</loc>
-    <lastmod>2026-03-30</lastmod>
+    <lastmod>2026-04-01</lastmod>
   </sitemap>
 </sitemapindex>