fix: corregir race condition en favoritos con Supabase INITIAL_SESSION

frontend/src/App.vue

@@ -1,5 +1,5 @@
 <script setup lang="ts">
-import { computed, onMounted, onUnmounted } from 'vue'
+import { computed, onMounted, onUnmounted, watch } from 'vue'
 import { RouterView, useRoute } from "vue-router";
 import { useI18n } from 'vue-i18n'
 import MainLayout from "./components/layouts/MainLayout.vue";
@@ -155,15 +155,24 @@ onMounted(() => {
     event_name: 'app_open',
     properties: { language: locale.value }
   })
-  // Load favorites if the user is already logged in
-  if (authStore.isAuthenticated) {
-    favoritesStore.loadFavorites()
-  }
   document.addEventListener('visibilitychange', handleVisibilityChange)
   window.addEventListener('pageshow', handlePageShow)
   window.addEventListener('focus', handleWindowFocus)
 })
 
+// Cargar favoritos cuando Supabase confirme la sesión (puede ser después de onMounted)
+// immediate:true cubre el caso donde la sesión ya está lista al arrancar
+const stopFavWatcher = watch(
+  () => authStore.isAuthenticated,
+  (authenticated) => {
+    if (authenticated && favoritesStore.favorites.length === 0 && !favoritesStore.isLoading) {
+      favoritesStore.loadFavorites()
+      stopFavWatcher() // Solo necesitamos cargarlo una vez al inicio
+    }
+  },
+  { immediate: true }
+)
+
 onUnmounted(() => {
   document.removeEventListener('visibilitychange', handleVisibilityChange)
   window.removeEventListener('pageshow', handlePageShow)