fix: comprehensive safe area implementation fixes for iOS video display

- Remove overflow-x: hidden from HeroSection.vue that was clipping video
- Delete duplicate .hero-video-container styles from voyage-layout.css
- Fix navigation to use env() directly instead of CSS variables
- Remove deprecated constant() syntax
- Add safe-area-test.html for testing safe area extension

The video should now properly extend under the iOS notch/Dynamic Island
while keeping content within safe areas.

apps/website/components/HeroSection.vue

@@ -237,9 +237,9 @@ onMounted(() => {
   pointer-events: none;
 }
 
-/* Container to prevent horizontal overflow */
+/* Container for hero section */
 .hero-voyage {
-  overflow-x: hidden !important;
+  /* Allow video to extend into safe area - no overflow clipping */
   max-width: 100vw !important;
   position: relative;
   min-height: 100vh;