refactor(admin): unify sortable/draggable/repeater list UI

- Add shared sortable-list.css, SORTABLE_LIST_ATTRS and AksSortHandle
- Migrate schema sortable, selected order, inline/modal repeater, sorter,
  floating buttons, footer tabbar and ticket prereply lists to the shared design
- Split AksField.vue (1885 -> 969 lines) into focused components/helpers
- Remove dead AksArrayTable/AksRepeaterField and move-up/down helpers
- Replace hardcoded colors and --n-* vars with --aksrt-color-* tokens

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

assets/admin/src/pages/content/FloatingButtonsSettings.vue

@@ -51,11 +51,9 @@
           <div class="float-settings__desc">设置并排序需要显示的按钮</div>
           <draggable
             v-model="form.items"
+            v-bind="SORTABLE_LIST_ATTRS"
             item-key="type"
-            handle=".float-btn-panel__handle"
-            ghost-class="float-settings__ghost"
-            animation="180"
-            class="float-settings__list"
+            class="aksrt-sortable"
           >
             <template #item="{ element, index }">
               <FloatBtnItemPanel :model-value="element" @update:model-value="updateItem(index, $event)" />
@@ -76,6 +74,7 @@ import draggable from 'vuedraggable'
 import api from '@/api'
 import PageHeader from '@/components/PageHeader.vue'
 import AksSaveBar from '@/components/form/AksSaveBar.vue'
+import { SORTABLE_LIST_ATTRS } from '@/components/form/sortable-options.js'
 import FloatBtnItemPanel from '@/components/floating/FloatBtnItemPanel.vue'
 import { defaultSettings, normalizeItems } from '@/components/floating/floating-defaults.js'
 
@@ -163,13 +162,13 @@ onMounted(loadSettings)
 
 .float-settings__desc {
   font-size: 12px;
-  color: var(--n-text-color-3, #999);
+  color: var(--aksrt-color-muted, #6F7A72);
 }
 
 .float-settings__label {
   margin-left: 12px;
   font-size: 13px;
-  color: var(--n-text-color-3, #999);
+  color: var(--aksrt-color-muted, #6F7A72);
 }
 
 .float-settings__section {
@@ -183,14 +182,4 @@ onMounted(loadSettings)
   font-weight: 600;
   font-size: 14px;
 }
-
-.float-settings__list {
-  display: flex;
-  flex-direction: column;
-  gap: 8px;
-}
-
-.float-settings__ghost {
-  opacity: 0.45;
-}
 </style>