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/components/form/field-dependency.js

@@ -0,0 +1,18 @@
+/**
+ * schema 字段的 dependsOn 规则求值。sourceValue 是规则引用的数据对象
+ * （fieldset 值 / repeater 行 / 弹窗草稿）。
+ */
+export function matchDependency(rule, sourceValue) {
+  if (!rule) return true
+  const source = sourceValue && typeof sourceValue === 'object' ? sourceValue : {}
+  if (rule.all) return rule.all.every(item => matchDependency(item, source))
+  if (rule.any) return rule.any.some(item => matchDependency(item, source))
+  const value = source[rule.key]
+  if (rule.operator === 'truthy') return !!value
+  if (rule.operator === 'falsy') return !value
+  if (rule.operator === 'not_empty') return Array.isArray(value) ? value.length > 0 : value !== '' && value != null
+  if (rule.operator === 'empty') return Array.isArray(value) ? value.length === 0 : value === '' || value == null
+  if (rule.operator === 'eq') return value === rule.value
+  if (rule.operator === 'neq') return value !== rule.value
+  return rule.value === undefined || value === rule.value
+}