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

src/Frontend/InlineStyleBuilder.php

@@ -131,7 +131,7 @@ class InlineStyleBuilder {
         }
 
         if (class_exists('\AKSRT\Settings\Settings') && !empty(\AKSRT\Settings\Settings::get_value('close_backdrop', false))) {
-            echo '<style id="aksrt-no-backdrop">.aksrt-header,.header-inner,.site-header,.header,.mobile-nav-overlay,.modal-backdrop,.aksrt-drawer-overlay,.aksrt-float-btn,.sidebar-inner{backdrop-filter:none!important;-webkit-backdrop-filter:none!important;background-color:var(--bg-card,#fff)!important}</style>' . "\n";
+            echo '<style id="aksrt-no-backdrop">.aksrt-header,.header-inner,.site-header,.header,.mobile-nav-overlay,.modal-backdrop,.aksrt-drawer-overlay,.sidebar-inner{backdrop-filter:none!important;-webkit-backdrop-filter:none!important;background-color:var(--bg-card,#fff)!important}</style>' . "\n";
         }
         echo '<style id="aksrt-runtime-components">'
             . '.aksrt-search-hot-keywords{display:flex;align-items:center;gap:10px;flex-wrap:wrap;margin-top:12px;font-family:var(--font-ui);}'