Responsive polish: pointer-events-none on animations, sticky header with scroll fade, desktop scroll-to-active fix, iOS audio unlock, player and UI tweaks

- Add pointer-events-none/select-none to feature cards, voice creator, and ControlUI mock
- Sticky header with gradient fade overlay (matching real app 3-layer technique)
- Fix desktop scroll-to-active: separate mobile/desktop card refs to prevent mobile refs overwriting desktop
- Scroll selected card to 2nd row when outside safe zone above generate box
- iOS Safari audio unlock via WaveSurfer's actual media element
- Player: accent fill play/pause button, padding on volume slider, remove close button
- Profile cards: fixed 143px height, mobile edge fades with scroll-aware left fade
- Generate box: accent effect pill when active, white fill sparkle icon, edge-aligned on desktop
- Voice creator: animated waveform background with height-based bars
- 12 profiles (added Attenborough, Zendaya, Obama) for 4-row grid with scroll

landing/src/components/Features.tsx

@@ -814,7 +814,9 @@ function FeatureCard({ feature }: { feature: (typeof FEATURES)[number] }) {
   return (
     <div className="rounded-lg border border-app-line bg-app-darkBox overflow-hidden">
       <LazyLoad>
-        <Animation />
+        <div className="pointer-events-none select-none">
+          <Animation />
+        </div>
       </LazyLoad>
       <div className="p-5">
         <div className="flex items-center gap-2 mb-2">