feat: add FavoritesService with Directus sync, union merge on login, localStorage migration

js/app.js

@@ -1,5 +1,6 @@
 import { i18n } from './i18n.js'
 import { auth } from './services/auth.js'
+import { favoritesService } from './services/favorites.js'
 import { setupGlobalErrorHandler } from './components/error-boundary.js'
 
 async function initApp() {
@@ -15,6 +16,7 @@ async function initApp() {
     
     // Restore auth session before loading components
     await auth.tryRestoreSession()
+    favoritesService.init()
 
     await import('./components/app-shell.js')