feat(skin): add audio skins for HTML and React presets (#772)

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

packages/skins/src/default/tailwind/components/surface.ts

@@ -0,0 +1,8 @@
+import { cn } from '@videojs/utils/style';
+
+export const surface = cn(
+  // Border and shadow
+  'ring ring-inset shadow-sm',
+  // Border to enhance contrast on lighter videos
+  'after:absolute after:inset-0 after:ring after:rounded-[inherit] after:pointer-events-none after:z-10'
+);