fix(user): normalize default avatar filename

inc/helpers/aksrt-avatar.php

@@ -44,7 +44,7 @@ if (!function_exists('aksrt_get_default_avatar_url')) {
 	function aksrt_get_default_avatar_url(): string {
 		return (string) apply_filters(
 			'aksrt_default_avatar_url',
-			get_theme_file_uri('assets/img/user/default avatar.svg')
+			get_theme_file_uri('assets/img/user/default-avatar.svg')
 		);
 	}
 }