Improve real-time sync speed and caching

- Reduced polling interval from 3s to 2s for faster updates
- Added revalidate = 0 to prevent Next.js caching
- Updates from other browsers now appear within 2 seconds
- Both home page and list detail pages sync faster

app/list/[id]/page.tsx

@@ -9,6 +9,7 @@ import InlineItemCreate from '@/components/InlineItemCreate'
 import ListDetailView from '@/components/ListDetailView'
 
 export const dynamic = 'force-dynamic'
+export const revalidate = 0
 
 export default async function ListDetailPage({ params }: { params: { id: string } }) {
   const session = await getServerSession(authOptions)