Move /settings/homepage onto a dedicated REST trait that stores Zibll
option IDs (home_posts_list_s, index_list_title, home_lists, exclude
posts/cats, list1 orderby). Reader exposes both canonical keys and
temporary aliases for existing front-end helpers; save path drops
superseded AKSRT-only keys. HomepageSettings.vue binds to the new
contract while remaining a Vue custom page.