api#347: сохранить part в именованных наборах и процентных контрактах

admin/tests/percent-migration.php

@@ -29,3 +29,6 @@ foreach([
  '{"utm":null}',
 ] as $i=>$source)migrationReject($source,'unsafe/ambiguous input rejected '.$i);
 echo "Raw percent migration complete\n";
+
+$partRaw='{"metadata":"keep","utm":{"part":{"default":"2","weights":{"1":1,"2":3}}}}';
+migrationCheck(PercentMigration::patch($partRaw)===str_replace('{"1":1,"2":3}','{"1":25,"2":75}',$partRaw),'part relative weights normalize only explicit numeric spans');