feat: implement multilingual support for sitemap and SEO, update structured data, and improve locale middleware configuration

resources/views/sitemap.blade.php

@@ -1,8 +1,14 @@
 {!! '<' . '?xml version="1.0" encoding="UTF-8"?' . '>' !!}
-<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
+<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"
+        xmlns:xhtml="http://www.w3.org/1999/xhtml">
     @foreach($urls as $url)
     <url>
         <loc>{{ $url['loc'] }}</loc>
+        @if(!empty($url['alternates']))
+            @foreach($url['alternates'] as $alt)
+                <xhtml:link rel="alternate" hreflang="{{ $alt['hreflang'] }}" href="{{ $alt['href'] }}"/>
+            @endforeach
+        @endif
         <lastmod>{{ $url['lastmod'] }}</lastmod>
         <changefreq>{{ $url['changefreq'] }}</changefreq>
         <priority>{{ $url['priority'] }}</priority>