fix(admin): replicate reference comment settings page 1:1

- Rewrite post_list/comment schema (PHP + JS) with the reference theme's
  field set, order, defaults and dependencies; smilie, comment location
  and quick-reply fields excluded
- Map PostDisplay::get_comment_display_settings() to the new keys without
  legacy fallback: close_comments, comment_paginate_type (ajax_lists),
  user_edit_comment master switch, WP comment_order for sorting
- Wire comment_box_hide visibility gate (signin / vip / vip_2 / auth)
- Drop dead comment settings (order/per_page/depth/avatar/hot threshold/
  empty text/city), the dead post_close_comments field, and city readers
  now fully owned by the IP-geo extension
- Add comment settings reference contract test

inc/helpers/aksrt-ip-geo.php

@@ -5,7 +5,7 @@
  * Gates:
  *   master: ip_geo_enabled
  *   surface: ip_geo_display ∈ {comment, user_home, user_center, post}
- *   comments: comment_city_s (+ comment_city_type) via comments/geo.php
+ *   comments: display + format fully owned by this extension via comments/geo.php
  *
  * Meta:
  *   comment → aksrt_comment_addr {country,province,city}