fix(migration): use correct system_config column names in Phase_100_002

The INSERT was using non-existent columns (config_group, label_ar, field_type).
The actual table has config_type, group_name, description_ar, is_editable.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

database/migrations/Phase_100_002_add_medical_grace_period.php

@@ -11,6 +11,15 @@ return function (\App\Core\Database $db): void {
 
     $configExists = $db->selectOne("SELECT 1 FROM system_config WHERE config_key = 'sa.medical_grace_days'");
     if (!$configExists) {
-        $db->raw("INSERT INTO system_config (config_key, config_value, config_group, label_ar, field_type, created_at, updated_at) VALUES ('sa.medical_grace_days', '14', 'sports_activity', 'مهلة تقديم الشهادة الطبية (بالأيام)', 'number', NOW(), NOW())");
+        $db->insert('system_config', [
+            'config_key'     => 'sa.medical_grace_days',
+            'config_value'   => '14',
+            'config_type'    => 'integer',
+            'group_name'     => 'sports_activity',
+            'description_ar' => 'مهلة تقديم الشهادة الطبية (بالأيام)',
+            'is_editable'    => 1,
+            'created_at'     => date('Y-m-d H:i:s'),
+            'updated_at'     => date('Y-m-d H:i:s'),
+        ]);
     }
 };