fix(journey): websocket sync across devices + 404 redirect

- broadcastJourneyEvent now excludes by socket ID instead of user ID,
  so other devices of the same user receive real-time updates (#615)
- Routes pass x-socket-id header through to broadcast functions
- loadJourney handles 404 gracefully — redirects to /journey with
  toast instead of infinite spinner (#616)

client/src/pages/JourneyDetailPage.tsx

@@ -79,7 +79,7 @@ export default function JourneyDetailPage() {
   const navigate = useNavigate()
   const toast = useToast()
   const { t } = useTranslation()
-  const { current, loading, loadJourney, updateEntry, deleteEntry, uploadPhotos, deletePhoto } = useJourneyStore()
+  const { current, loading, notFound, loadJourney, updateEntry, deleteEntry, uploadPhotos, deletePhoto } = useJourneyStore()
   const mapRef = useRef<JourneyMapHandle>(null)
   const fullMapRef = useRef<JourneyMapHandle>(null)
   const [activeLocationId, setActiveLocationId] = useState<string | null>(null)
@@ -97,6 +97,13 @@ export default function JourneyDetailPage() {
     if (id) loadJourney(Number(id))
   }, [id])
 
+  useEffect(() => {
+    if (notFound) {
+      toast.error(t('journey.notFound'))
+      navigate('/journey')
+    }
+  }, [notFound])
+
   // WebSocket real-time updates
   useEffect(() => {
     if (!id) return