feat: notification system via Mercure for scraping events

- NotificationInterface: add sendInfo() and sendWarning() levels
- SymfonyNotification: implement new levels (publishes to 'notifications' topic)
- ChapterScrapingStarted: carry mangaTitle + chapterNumber, now dispatched
- ScrapeChapterHandler: dispatch ChapterScrapingStarted before scraping loop
- ScrapingEventSubscriber: wire NotificationInterface for started/scraped/failed events
- useMercureNotifications: new global Vue composable subscribing to 'notifications' topic
- App.vue: mount useMercureNotifications() at app root
- SendTestNotificationCommand: `app:notify:test --type --message` for dev/prod testing

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/Domain/Shared/Domain/Contract/NotificationInterface.php

@@ -6,18 +6,13 @@ namespace App\Domain\Shared\Domain\Contract;
 
 interface NotificationInterface
 {
-    /**
-     * Envoie une notification de succès
-     */
     public function sendSuccess(string $message): void;
 
-    /**
-     * Envoie une notification d'erreur
-     */
     public function sendError(string $message): void;
 
-    /**
-     * Envoie une notification avec un statut personnalisé
-     */
+    public function sendInfo(string $message): void;
+
+    public function sendWarning(string $message): void;
+
     public function sendUpdate(array $data): void;
 }