feat(admin): replicate reference post-page settings page 1:1

- rewrite post_list.page schema (JS+PHP 2.0.0) with the reference field set:
  three cover types with option fieldsets (image 20-200% / slide CFS_Module::slide
  full config with nested dependsOn / video 0-200%), hide-time, p_indent,
  breadcrumbs (home-text as switcher), prevnext, authordesc, maxheight slider,
  yiyan block, copyright, button toptext, front/after content, related posts
- migrate share_s to share page basic group and post_rewards_* to users
  features rewards group (runtime keys unchanged)
- remap get_post_page_settings() to reference keys, normalize slide cover
  option, hardcode non-reference runtime flags (reading progress, favorites,
  author card), drop dual-path legacy aliases
- wire slide option into aksrt_render_slider (effect/direction/spaceBetween/
  speed/interval/loop/autoplay/nav/pagination, scale vs fixed-height modes),
  clamp image scale 20-200 and video scale 0-200 with 16:9 fallback,
  wire p_indent container class + CSS, resync frontend-tags fallback and
  FacadeBulk fallback, remap PostMetaBox cover keys
- add post-page reference contract test; update stale cover-height and
  user-features contract tests

Validation: node --test 464/464 pass, audit-admin-contracts errors=0,
vite build ok, build-public-assets ok, php -l clean.

assets/css/frontend/single-post/content.css

@@ -137,6 +137,11 @@ article.article.box-body,
   margin: 0 0 1.5em;
 }
 
+/* 段落首行缩进（参考主题 post_p_indent_s：开启后正文段落首行缩进 2em）。 */
+.wp-posts-content.p-indent p {
+  text-indent: 2em;
+}
+
 :is(.entry-content, .wp-posts-content) h2 {
   font-size: 20px;
   font-weight: 700;