Enhance configuration and layout: add environment variables, improve metadata, and update content section keys for consistency

Co-authored-by: Copilot <copilot@github.com>

src/pages/[collection]/[...slug].astro

@@ -49,7 +49,11 @@ if (entry.id !== "index") {
 const { Content } = await render(entry);
 ---
 
-<Layout title={entry.data.title} breadcrumbs={breadcrumbs}>
+<Layout
+  title={entry.data.title}
+  description={entry.data.description}
+  breadcrumbs={breadcrumbs}
+>
   <div class="prose-radium">
     <Content class="prose-radium" />
   </div>