Füge Fallback-Logik für Anzeigen hinzu: Lade iframe-Backup, wenn nach 3s kein Ad im Platzhalter erscheint

client/src/components/HeaderAdBanner.vue

@@ -167,6 +167,33 @@ async function renderPropeller() {
 
     // Start observing shortly after script insertion to allow provider to run
     setTimeout(observeAndRelocate, 100);
+
+    // Fallback: wenn nach Script‑Load innerhalb 3s kein Ad im Placeholder erscheint,
+    // lade ein iframe‑Backup. Das erhöht die Chance, ein sichtbares Banner im Header zu zeigen.
+    setTimeout(() => {
+      try {
+        const ph = adContainer.value.querySelector('.propeller-ad-placeholder');
+        const hasChild = ph && ph.children && ph.children.length > 0;
+        const height = ph ? parseInt(getComputedStyle(ph).height || '0', 10) : 0;
+        if (!hasChild && (!height || height === 0)) {
+          console.log('Ad placeholder empty — inserting iframe fallback');
+          const iframe = document.createElement('iframe');
+          iframe.width = '100%';
+          iframe.height = '90';
+          iframe.frameBorder = '0';
+          iframe.scrolling = 'no';
+          iframe.style.border = '0';
+          iframe.title = 'Advertisement';
+          // Fallback URL: attempt to call tag URL with slot param — may be accepted by provider
+          iframe.src = `${propScriptUrl}?slot=${encodeURIComponent(propSlotId)}&responsive=1`;
+          ph.innerHTML = '';
+          ph.appendChild(iframe);
+          try { window.dispatchEvent(new CustomEvent('ads:fallback-inserted',{detail:{provider:'propeller',zone:propSlotId}})); } catch {}
+        }
+      } catch (e) {
+        console.warn('Fallback insertion failed', e);
+      }
+    }, 3000);
   } catch (err) {
     console.warn('Propeller ad load failed', err);
   }