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/css/frontend/overlay-primitives.css

@@ -55,16 +55,6 @@ html.dark .footer-tabbar--glass {
   box-shadow: 0 -10px 28px rgba(0, 0, 0, 0.32);
 }
 
-/* ============================================================
- * Glass on floating buttons (lighter blur: saturate(2) blur(10px))
- * ============================================================ */
-.float-right--glass .float-btn {
-  -webkit-backdrop-filter: saturate(2) blur(10px);
-  backdrop-filter: saturate(2) blur(10px);
-  background: var(--float-btn-bg);
-  border-color: transparent;
-}
-
 /* ============================================================
  * Scroll shadow on glass header (legacy: .body-scroll .header)
  * ============================================================ */