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/footer/part.css

@@ -18,101 +18,6 @@
     .hide-on-pc { display: none !important; }
 }
 
-/* ============================================================
- * 浮动右侧按钮组（模仿 legacy float-right）
- * ============================================================ */
-/* 对齐 legacy: bottom 60px, z-index 1030 */
-.float-right-btns {
-    position: fixed;
-    right: 20px;
-    bottom: 60px;
-    z-index: 1030;
-    display: flex;
-    flex-direction: column;
-    gap: 8px;
-    transition: opacity 0.3s ease;
-}
-
-/* 对齐 legacy: 40px, 1.4em icon */
-.float-btn {
-    display: flex;
-    align-items: center;
-    justify-content: center;
-    width: 40px;
-    min-height: 40px;
-    border-radius: 50%;
-    border: none;
-    background: var(--float-btn-bg);
-    color: var(--color-ink-3);
-    box-shadow: var(--shadow-sm);
-    cursor: pointer;
-    transition: transform var(--dur-fast) var(--ease), box-shadow var(--dur-fast) var(--ease), background var(--dur-fast) var(--ease), color var(--dur-fast) var(--ease);
-    font-size: 1.4em;
-    text-decoration: none;
-}
-
-.float-btn:hover {
-    transform: translateY(-2px);
-    box-shadow: var(--shadow);
-    color: var(--color-primary);
-    background: var(--surface-page);
-    text-decoration: none;
-}
-
-.float-btn:active {
-    transform: scale(0.95);
-}
-
-/* 回到顶部按钮 — 滚动后显示 */
-.float-btn--top {
-    opacity: 0;
-    visibility: hidden;
-    transition: opacity 0.3s ease, visibility 0.3s ease, transform 0.2s ease;
-}
-
-.float-btn--top.is-visible {
-    opacity: 1;
-    visibility: visible;
-    display: flex;
-}
-
-/* 主题切换按钮 */
-#float-theme-toggle .float-btn__icon-moon {
-    display: none !important;
-}
-
-#float-theme-toggle .float-btn__icon-sun {
-    display: inline-block !important;
-}
-
-#float-theme-toggle[aria-pressed="true"] .float-btn__icon-moon,
-.theme-dark #float-theme-toggle .float-btn__icon-moon,
-html.dark #float-theme-toggle .float-btn__icon-moon,
-body.dark-theme #float-theme-toggle .float-btn__icon-moon {
-    display: inline-block !important;
-}
-
-#float-theme-toggle[aria-pressed="true"] .float-btn__icon-sun,
-.theme-dark #float-theme-toggle .float-btn__icon-sun,
-html.dark #float-theme-toggle .float-btn__icon-sun,
-body.dark-theme #float-theme-toggle .float-btn__icon-sun {
-    display: none !important;
-}
-
-/* 移动端隐藏浮动按钮（用 tabbar 代替） */
-@media (max-width: 767px) {
-    .float-right-btns {
-        right: 12px;
-        bottom: 80px;
-    }
-
-    .float-btn {
-        width: 38px;
-        height: 38px;
-        font-size: 14px;
-    }
-}
-
 /* ============================================================
  * 移动端底部 Tab 栏（模仿 legacy footer-tabbar）
  * ============================================================ */
@@ -603,12 +508,6 @@ html.dark .site-footer {
     background: var(--surface-1);
 }
 
-.theme-dark .float-btn,
-html.dark .float-btn {
-    background: var(--float-btn-bg);
-    box-shadow: var(--shadow-sm);
-}
-
 .theme-dark .footer-tabbar,
 html.dark .footer-tabbar {
     background: var(--blur-bg);