refactor(admin): drop homepage mixed content model and publish-resource preset

inc/classes/settings/trait-aksrt-settings-homepage-reader.php

@@ -31,9 +31,9 @@ trait AKSRT_Settings_Homepage_Reader {
     }
 
     /**
-     * Homepage content model.
+     * Homepage always uses ordinary posts.
      *
-     * @return string 'post' or 'mixed'
+     * @return string Always 'post'.
      */
     public static function homepage_content_model(): string {
         return AKSRT_Settings_Home_Cms::homepage_content_model();