Move model observers onto attributes and tidy provider bindings.

Register observers with ObservedBy, bind the comment spam classifier, and keep AppServiceProvider focused on application wiring.

app/Models/ArtworkFavourite.php

@@ -2,22 +2,25 @@
 
 namespace App\Models;
 
+use App\Observers\ArtworkFavouriteObserver;
+use Carbon\Carbon;
+use Illuminate\Database\Eloquent\Attributes\ObservedBy;
 use Illuminate\Database\Eloquent\Model;
 use Illuminate\Database\Eloquent\Relations\BelongsTo;
 
 /**
  * Represents a user's "favourite" bookmark on an artwork.
  *
- * @property int         $id
- * @property int         $user_id
- * @property int         $artwork_id
- * @property int|null    $legacy_id   Original favourite_id from the old site
- * @property \Carbon\Carbon $created_at
- * @property \Carbon\Carbon $updated_at
- *
+ * @property int $id
+ * @property int $user_id
+ * @property int $artwork_id
+ * @property int|null $legacy_id Original favourite_id from the old site
+ * @property Carbon $created_at
+ * @property Carbon $updated_at
  * @property-read User    $user
  * @property-read Artwork $artwork
  */
+#[ObservedBy([ArtworkFavouriteObserver::class])]
 class ArtworkFavourite extends Model
 {
     protected $table = 'artwork_favourites';
@@ -29,9 +32,9 @@ class ArtworkFavourite extends Model
     ];
 
     protected $casts = [
-        'user_id'    => 'integer',
+        'user_id' => 'integer',
         'artwork_id' => 'integer',
-        'legacy_id'  => 'integer',
+        'legacy_id' => 'integer',
     ];
 
     // ── Relations ──────────────────────────────────────────────────────────