enhance(backend): notify new login (#14673)

* wip

* Update CHANGELOG.md

* wip

* fix

* Update index.d.ts

* Update SigninService.ts

* Update MkNotification.vue

packages/frontend-shared/js/const.ts

@@ -68,6 +68,7 @@ export const notificationTypes = [
 	'roleAssigned',
 	'achievementEarned',
 	'exportCompleted',
+	'login',
 	'test',
 	'app',
 ] as const;