Adjust ad positioning on article pages for better display

Modify `PageSideAds` component to accept `contentHalfWidth` prop for dynamic ad placement based on content container width, and update specific pages (article, about, datenschutz, empfang, impressum, search) to pass the correct values.

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client/src/pages/impressum.tsx

@@ -9,7 +9,7 @@ export default function ImpressumPage() {
   return (
     <div className="min-h-screen bg-background">
       <Header />
-      <PageSideAds />
+      <PageSideAds contentHalfWidth={384} />
       <main className="max-w-3xl mx-auto px-4 sm:px-6 lg:px-8 py-8">
         <div className="flex items-center gap-3 mb-8">
           <Scale className="w-7 h-7 text-primary" />