fix: homepage overlay blocker and carousel auto-advance

- Add pointer-events:none to ListeningMode fly-transition wrapper div in
  +layout.svelte so the exiting animation div never blocks page interaction
- Add pointer-events:auto to ListeningMode root div so it still captures
  all touch/click events correctly despite the parent being pointer-events:none
- Rewrite carousel auto-advance using $effect + autoAdvanceSeed pattern:
  replaces the stale-closure setInterval in resetAutoAdvance() with a
  reactive $effect that owns the interval and re-starts cleanly on manual
  navigation by bumping a seed counter

ui/src/lib/components/ListeningMode.svelte

@@ -256,6 +256,7 @@
 		transition: {isDragging ? 'none' : 'transform 0.32s cubic-bezier(0.32,0.72,0,1), opacity 0.32s ease'};
 		will-change: transform;
 		touch-action: pan-x;
+		pointer-events: auto;
 	"
 	ontouchstart={onTouchStart}
 	ontouchend={onTouchEnd}