fix(header): wire multi-function page-type enable like zibll

Connect header_components_show_on through aksrt_header_slide_is_show with
zibll page-type matching, drop the homepage-only gate, align admin options,
apply nav color, enqueue by is_show, remove dead float-btn schema, and
consume footer_tabbar_single extend mode on post singles.

assets/admin/src/constants/sections/page-display.js

@@ -86,16 +86,6 @@ export const pageDisplaySection = {
       desc: '首页内容模型、主列表、分类 Tab 与首页交互配置。',
       component: 'HomepageSettings',
     }),
-    schemaPage({
-      key: 'page-display-float-btn',
-      name: 'PageDisplayFloatBtn',
-      label: '悬浮按钮',
-      route: '/page-display/float-btn',
-      title: '悬浮按钮',
-      desc: '悬浮按钮的显示规则、样式与滚动隐藏设置。',
-      canonicalDomain: 'page_display',
-      section: 'float-btn',
-    }),
     schemaPage({
       key: 'page-display-category',
       name: 'PageDisplayCategory',