fixup! fix: set createdAt timestamp for local attachments

Author: kesselb

lib/Migration/Version5006Date20251023224608.php

@@ -28,7 +28,7 @@ public function changeSchema(IOutput $output, Closure $schemaClosure, array $opt
 
 		$attachments = $schema->getTable('mail_attachments');
 
-		// Ensure created_at is NOT NULL and has no default, so app must set it.
+		// Drop default value for created_at column
 		if ($attachments->hasColumn('created_at')) {
 			$attachments->modifyColumn('created_at', [
 				'default' => null,