refactor: remove realtime visitors detail page

Remove the individual session journey page and make the live visitor
count a static indicator. Prepares for the new aggregated User Journeys
feature (v0.17).

components/dashboard/RealtimeVisitors.tsx

@@ -1,19 +1,11 @@
-'use client'
-
-import { useRouter } from 'next/navigation'
-
 interface RealtimeVisitorsProps {
   count: number
-  siteId?: string
 }
 
-export default function RealtimeVisitors({ count, siteId }: RealtimeVisitorsProps) {
-  const router = useRouter()
-  
+export default function RealtimeVisitors({ count }: RealtimeVisitorsProps) {
   return (
-    <div 
-      onClick={() => siteId && router.push(`/sites/${siteId}/realtime`)}
-      className={`bg-white dark:bg-neutral-900 border border-neutral-200 dark:border-neutral-800 rounded-2xl p-6 ${siteId ? 'cursor-pointer hover:border-neutral-300 dark:hover:border-neutral-700 transition-colors' : ''}`}
+    <div
+      className="bg-white dark:bg-neutral-900 border border-neutral-200 dark:border-neutral-800 rounded-2xl p-6"
     >
       <div className="flex items-center justify-between mb-2">
         <div className="text-sm text-neutral-600 dark:text-neutral-400">

components/dashboard/SiteNav.tsx

@@ -26,7 +26,7 @@ export default function SiteNav({ siteId }: SiteNavProps) {
 
   const isActive = (href: string) => {
     if (href === `/sites/${siteId}`) {
-      return pathname === href || pathname === `${href}/realtime`
+      return pathname === href
     }
     return pathname.startsWith(href)
   }