fix(map): prevent ghost polylines and improve ETA accuracy.

- Added cancel tokens to avoid 'traces' on map after route removal.
- Fixed math bug in ETA proportion calculating 16.6% less time than real.
- Set average bus speed to 30km/h for more realistic calculations.

frontend/src/views/MapView.vue

@@ -472,7 +472,7 @@ async function highlightOptimalStopForRoute() {
   if (!userCoords.value || routeStore.selectedRouteStops.length === 0) return;
   
   try {
-    await encontrarParadaCercana(userCoords.value, routeStore.selectedRouteStops as BusStop[], map.value || undefined);
+    await encontrarParadaCercana(userCoords.value, routeStore.selectedRouteStops as BusStop[], map.value || undefined, currentCancelToken);
   } catch (e) {
     console.error('Error calculating optimal stop:', e);
   }