fix(landing): reset fading when reduced motion cuts the loop short

showFinished (added when wiring up the prefers-reduced-motion change
listener) set the finished phase but left fading true if the preference
flipped mid reset-fade, leaving HeroChatLoop stuck at opacity-0.

Author: waleedlatif1

apps/sim/app/(landing)/components/hero/components/hero-platform-loop/hero-platform-loop.tsx

@@ -101,6 +101,7 @@ export function HeroPlatformLoop() {
 
     const showFinished = () => {
       clearScheduled()
+      setFading(false)
       setPhase('reply')
       setStageOpen(true)
       setBuiltCount(STAGE_BLOCKS.length)