Use customer-sent video for mobile hero background

Old hero-bg-mobile.mp4 kept as fallback.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/routes/+page.svelte

@@ -183,7 +183,7 @@
     <source src="/hero-bg.mp4" type="video/mp4">
   </video>
   <video class="sm:hidden absolute inset-0 w-full h-full object-cover" autoplay muted loop playsinline>
-    <source src="/hero-bg-mobile.mp4" type="video/mp4">
+    <source src="/hero-bg-mobile-v2.mp4" type="video/mp4">
   </video>
   <div class="absolute inset-0 bg-black/60"></div>