StudioCMS: REST API Missing Rank Check Allows Admin to Create Peer Admin Accounts

StudioCMS is a server-side-rendered, Astro native, headless content management system. Prior to 0.4.3, the REST API createUser endpoint uses string-based rank checks that only block creating owner accounts, while the Dashboard API uses indexOf-based rank comparison that prevents creating users at or above your own rank. This inconsistency allows an admin to create additional admin accounts via the REST API, enabling privilege proliferation and persistence. This vulnerability is fixed in 0.4.3.