Place ads within article content instead of at the end

Add a placeholder label for ads in the article to indicate their position, as AdSense ads do not render in development environments.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: 517dfa7b-26ac-463d-a6e1-a58c6df97188
Replit-Commit-Checkpoint-Type: full_checkpoint
Replit-Commit-Event-Id: 28e1d070-0b2f-4cb5-b3c4-80edd0cb5ec9
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/f209e72a-0939-48fa-84fc-57854de71967/517dfa7b-26ac-463d-a6e1-a58c6df97188/VgutZ7W
Replit-Helium-Checkpoint-Created: true

client/src/components/adsense.tsx

@@ -92,13 +92,15 @@ export function ArticleCardAd() {
 
 export function InArticleAd() {
   return (
-    <AdSense
-      slot="4154017639"
-      format="fluid"
-      layout="in-article"
-      style={{ display: "block", textAlign: "center" }}
-      className="my-8"
-    />
+    <div className="my-8 py-4 border-y border-border/30">
+      <div className="text-[10px] text-muted-foreground/40 text-center mb-2 uppercase tracking-widest">Anzeige</div>
+      <AdSense
+        slot="4154017639"
+        format="fluid"
+        layout="in-article"
+        style={{ display: "block", textAlign: "center" }}
+      />
+    </div>
   );
 }