add explicit set levels

backend/app/Set/SetLevelModel.php

@@ -0,0 +1,38 @@
+<?php
+
+namespace App\Set;
+
+use Illuminate\Database\Eloquent\Attributes\Fillable;
+use Illuminate\Database\Eloquent\Builder;
+use Illuminate\Database\Eloquent\Model;
+
+/**
+ * @property int $id
+ * @property int $set_id
+ * @property string $kind
+ * @property int $depth
+ *
+ * @method static Builder<static>|SetLevelModel newModelQuery()
+ * @method static Builder<static>|SetLevelModel newQuery()
+ * @method static Builder<static>|SetLevelModel query()
+ *
+ * @mixin \Eloquent
+ */
+#[Fillable(['set_id', 'kind', 'depth'])]
+class SetLevelModel extends Model
+{
+    protected $table = 'set_levels';
+
+    public $timestamps = false;
+
+    /**
+     * @return array<string, string>
+     */
+    protected function casts(): array
+    {
+        return [
+            'set_id' => 'integer',
+            'depth' => 'integer',
+        ];
+    }
+}