feat(web): embed video on detail page via nocookie iframe

Responsive 16:9 youtube-nocookie iframe rendered when the id is valid;
omitted (graceful) otherwise so summary/highlights/takeaways still show.
Regenerated views_templ.go.

internal/web/views.templ

@@ -106,6 +106,18 @@ templ DetailPage(r store.SummaryRow) {
 					<span class="badge" title="summarized with the fallback model" aria-label="summarized with the fallback model">fallback</span>
 				}
 			</p>
+			if url, ok := embedURL(r.ProviderVideoID); ok {
+				<div class="embed">
+					<iframe
+						src={ url }
+						title={ displayTitle(r) }
+						loading="lazy"
+						referrerpolicy="strict-origin-when-cross-origin"
+						allow="accelerometer; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share"
+						allowfullscreen
+					></iframe>
+				</div>
+			}
 			if r.URL != "" {
 				<p class="source"><a href={ externalURL(r.URL) } rel="noopener noreferrer">watch on source ↗</a></p>
 			}