Allow artworks to have one primary category and extra secondaries.

Keep artwork_category as membership, store a deterministic primary_category_id, and let upload plus studio pick up to five additional same-type categories without changing canonical URLs.

app/Http/Controllers/Api/DiscoveryNegativeSignalController.php

@@ -174,7 +174,7 @@ final class DiscoveryNegativeSignalController extends Controller
     }
 
     /**
-     * @param array<string, mixed> $meta
+     * @param  array<string, mixed>  $meta
      */
     private function recordFeedbackEvent(int $userId, int $artworkId, string $eventType, ?string $algoVersion = null, array $meta = []): void
     {
@@ -182,10 +182,9 @@ final class DiscoveryNegativeSignalController extends Controller
             return;
         }
 
-        $categoryId = DB::table('artwork_category')
-            ->where('artwork_id', $artworkId)
-            ->orderBy('category_id')
-            ->value('category_id');
+        $categoryId = DB::table('artworks')
+            ->where('id', $artworkId)
+            ->value('primary_category_id');
 
         DB::table('user_discovery_events')->insert([
             'event_id' => (string) Str::uuid(),