Add two new ad formats to blog articles for increased revenue

Integrates an interstitial overlay ad and a parallax ad into article pages to display advertisements.

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client/src/components/parallax-ad.tsx

@@ -0,0 +1,19 @@
+import AdSense from "./adsense";
+
+export default function ParallaxAd() {
+  return (
+    <div className="relative" data-testid="parallax-ad-wrapper">
+      <div className="sticky top-0 h-[350px] flex items-center justify-center bg-background z-0">
+        <div className="text-center w-full max-w-lg mx-auto">
+          <div className="text-[10px] text-muted-foreground/40 text-center mb-2 uppercase tracking-widest">Anzeige</div>
+          <AdSense
+            slot="2398082838"
+            format="rectangle"
+            style={{ display: "block", minHeight: "250px" }}
+          />
+        </div>
+      </div>
+      <div className="h-[350px]" aria-hidden="true" />
+    </div>
+  );
+}