feat(video): add YouTube lightbox to benefits section

Replaces static video link with a self-contained VideoCard component
that opens a native <dialog> lightbox with autoplay on open and
iframe src teardown on close. Includes pulsing ring animation on the
play button and a rounded-triangle SVG icon.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

www/src/types/home-sections.ts

@@ -26,7 +26,8 @@ export interface BenefitsSection {
   heading: string;
   subheading: string;
   items: string[];
-  videoHref: string;
+  videoUrl: string;
+  videoTitle: string;
   videoImage: string;
   videoImageAlt: string;
 }