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/Command/SendTestNotificationCommand.php

@@ -0,0 +1,55 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Command;
+
+use App\Domain\Shared\Domain\Contract\NotificationInterface;
+use Symfony\Component\Console\Attribute\AsCommand;
+use Symfony\Component\Console\Command\Command;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Input\InputOption;
+use Symfony\Component\Console\Output\OutputInterface;
+
+#[AsCommand(
+    name: 'app:notify:test',
+    description: 'Envoie une notification de test via Mercure (utile en dev/prod pour vérifier le système)',
+)]
+class SendTestNotificationCommand extends Command
+{
+    public function __construct(
+        private readonly NotificationInterface $notification
+    ) {
+        parent::__construct();
+    }
+
+    protected function configure(): void
+    {
+        $this
+            ->addOption('type', 't', InputOption::VALUE_REQUIRED, 'Type de notification : info, success, error, warning', 'info')
+            ->addOption('message', 'm', InputOption::VALUE_REQUIRED, 'Message à envoyer', 'Notification de test depuis Mangarr');
+    }
+
+    protected function execute(InputInterface $input, OutputInterface $output): int
+    {
+        $type = $input->getOption('type');
+        $message = $input->getOption('message');
+
+        $allowed = ['info', 'success', 'error', 'warning'];
+        if (!in_array($type, $allowed, true)) {
+            $output->writeln(sprintf('<error>Type invalide "%s". Valeurs acceptées : %s</error>', $type, implode(', ', $allowed)));
+            return Command::FAILURE;
+        }
+
+        match ($type) {
+            'success' => $this->notification->sendSuccess($message),
+            'error'   => $this->notification->sendError($message),
+            'warning' => $this->notification->sendWarning($message),
+            default   => $this->notification->sendInfo($message),
+        };
+
+        $output->writeln(sprintf('<info>[%s] Notification envoyée : %s</info>', strtoupper($type), $message));
+
+        return Command::SUCCESS;
+    }
+}