add json config and its manager class

+ rewrite logic to prevent removing last admin role
+ handle showing users on login and enabling guest

manage.py

@@ -44,7 +44,7 @@ app = create_api()
 app.static_folder = get_home_res_path("client")
 
 # INFO: Routes that don't need authentication
-blacklist_routes = {"/auth/login", "/auth/users"}
+blacklist_routes = {"/auth/login", "/auth/users", "/auth/logout"}
 blacklist_extensions = {".webp"}.union(getClientFilesExtensions())