refactor: embed film data directly in batch messages

Avoid re-parsing the entire CSV file in each batch handler by including
the film data in the message payload itself.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/MessageHandler/ProcessImportMessageHandler.php

@@ -56,11 +56,18 @@ readonly class ProcessImportMessageHandler
             $import->setStatus(Import::STATUS_PROCESSING);
             $this->em->flush();
 
-            for ($i = 0; $i < $totalBatches; $i++) {
+            $batches = array_chunk($ltbxdMovies, self::BATCH_SIZE);
+            foreach ($batches as $batch) {
+                $films = array_map(fn ($movie) => [
+                    'name' => $movie->getName(),
+                    'year' => $movie->getYear(),
+                    'ltbxdUri' => $movie->getLtbxdUri(),
+                    'date' => $movie->getDate()->format('Y-m-d'),
+                ], $batch);
+
                 $this->bus->dispatch(new ImportFilmsBatchMessage(
                     importId: $import->getId(),
-                    offset: $i * self::BATCH_SIZE,
-                    limit: self::BATCH_SIZE,
+                    films: $films,
                 ));
             }
         } catch (\Throwable $e) {