fix: resolve blank screen on return from external links

frontend/src/stores/shuttle.ts

@@ -26,12 +26,25 @@ export const useShuttleStore = defineStore('shuttle', () => {
         }
     }
 
+    // Recarga silenciosa: no activa el spinner (para refocus desde background)
+    async function silentReload() {
+        if (shuttles.value.length === 0) { return loadShuttles() }
+        error.value = null
+        try {
+            shuttles.value = await shuttlesService.getAllShuttles(filters.value)
+        } catch (e) {
+            console.error('Error silent-reloading shuttles:', e)
+            // No mostrar error si ya hay datos
+        }
+    }
+
     return {
         shuttles,
         isLoading,
         error,
         filters,
         loadShuttles,
+        silentReload,
     }
 }, {
     persist: {