feat(float): rebuild right floating buttons 1:1 with reference theme

- Storage: aksrt_floating_buttons now uses reference float_btn shape
  (fixed 8 sortable types, more-buttons group); single source of
  defaults/sanitize in AKSRT\Settings\FloatButtons
- Admin SPA: CSF-parity page split into components/floating/*
- Frontend: aksrt_float_right() on wp_footer mirrors zib_float_right()
  (wp_is_mobile, PC tooltip, toggle-theme, ontop/scrollTopTo, qrcode,
  wechat/qq, pay_vip, add, more)
- CSS: floating-buttons.css rewritten from reference rules; legacy float
  rules removed from main/part/shell/overlay-primitives
- Remove dead code: reorder route/API, get_floating_buttons_items,
  floatingSchema, floatActionsId, float-theme-toggle bindings,
  common/floating.css, aksrt-runtime-win.php, .aksrt-float-btn

assets/admin/src/schema/sections/global/floating.js

@@ -1,8 +0,0 @@
-export const floatingSchema = {
-  key: 'global.floating',
-  title: '右侧悬浮按钮',
-  icon: 'fa fas fa-ellipsis-v',
-  description: '页面右侧浮动按钮的显示与配置。',
-  defaults: {},
-  groups: [],
-}

assets/admin/src/schema/sections/global/index.js

@@ -9,7 +9,6 @@ import { layoutSchema } from './layout.js'
 import { searchSchema } from './search.js'
 // Email schema is served by the PHP template catalog to keep defaults and fields canonical.
 import { tabbarSchema } from './tabbar.js'
-import { floatingSchema } from './floating.js'
 import { i18nSchema } from './i18n.js'
 import { customCodeSchema } from './custom-code.js'
 import { seoSchema } from './seo.js'
@@ -23,7 +22,6 @@ export const globalSchemas = {
   search: searchSchema,
   email: null,
   tabbar: tabbarSchema,
-  floating: floatingSchema,
   i18n: i18nSchema,
   'custom-code': customCodeSchema,
   seo: seoSchema,