refactor: rename the theme brand and every identifier from AKSRT to Jio

Full-project rename. `git grep -i aksrt` is now empty apart from the
DBMigrator 3.3.0 changelog note that documents the rename itself.

Code identifiers
- PHP namespace AKSRT\ -> Jio\ (composer PSR-4 + 378 declarations)
- global constants AKSRT_* -> JIO_* (VERSION/DIR/URI, PAY_TYPE_*, CAPTCHA_*)
- procedural functions, hooks, options, meta keys, table names,
  cookies, query vars, ajax actions and nonces: aksrt_ -> jio_
- text domain aksrt -> jio; Theme Name -> Jio
- JS globals: aksrtData/aksrtAdminData/... -> jioData/jioAdminData/...,
  window.AKSRTCaptcha & friends -> window.JioCaptcha, Aksrt* -> Jio*
- Vue components Aks*.vue -> Jio*.vue (15 files renamed + imports)
- CSS classes/data-attrs/custom properties: aksrt- -> jio-
- REST namespace aksrt/v1 -> jio/v1 (incl. payment gateway callbacks)

Storage layer
- DB tables {prefix}aksrt_* -> {prefix}jio_*; SCHEMA_VERSION 3.2.0 -> 3.3.0
  so dbDelta creates the new names on install
- widget id_base aksrt_widget_* -> jio_widget_*
- uninstall.php drop list rebuilt from the actual migrator tables
  (dropped 3 stale entries, added the 17 missing ones)

Removed
- hardcoded https://api.aksrt.com/version.json default update endpoint;
  get_endpoint() now reads the 「更新端点」 setting and do_check() no-ops
  when it is empty

Files renamed: inc/helpers/aksrt-*.php -> jio-*.php (54),
assets/admin/src/components/form/Aks*.vue -> Jio*.vue (15).
Build artifacts regenerated: assets/css/build, assets/js/runtime,
assets/admin/build.

Verified: audit-psr4-paths errors=0, audit-admin-contracts errors=0
(warnings=56, unchanged baseline), 813/813 widget-system tests,
44/44 phpunit, php -l clean across all PHP.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

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

@@ -1,5 +1,5 @@
 <template>
-  <div class="aksrt-page-container content-page">
+  <div class="jio-page-container content-page">
     <PageHeader title="右侧悬浮按钮" desc="显示在页面右侧的悬浮按钮，支持排序及添加自定义按钮。" />
 
     <n-spin :show="loading" style="width: 100%; min-height: 200px;">
@@ -7,8 +7,8 @@
         <b>全局悬浮按钮：</b>显示在页面右侧的悬浮按钮，支持排序及添加自定义按钮
       </n-alert>
 
-      <n-card class="aksrt-section-card">
-        <n-form :model="form" label-placement="left" label-width="160" class="aksrt-form">
+      <n-card class="jio-section-card">
+        <n-form :model="form" label-placement="left" label-width="160" class="jio-form">
           <n-form-item label="按钮样式">
             <n-radio-group v-model:value="form.style">
               <n-space>
@@ -53,7 +53,7 @@
             v-model="form.items"
             v-bind="SORTABLE_LIST_ATTRS"
             item-key="type"
-            class="aksrt-sortable"
+            class="jio-sortable"
           >
             <template #item="{ element, index }">
               <FloatBtnItemPanel :model-value="element" @update:model-value="updateItem(index, $event)" />
@@ -63,7 +63,7 @@
       </n-card>
     </n-spin>
 
-    <AksSaveBar :dirty="dirty" :saving="saving" @save="handleSave" @reload="loadSettings" />
+    <JioSaveBar :dirty="dirty" :saving="saving" @save="handleSave" @reload="loadSettings" />
   </div>
 </template>
 
@@ -73,7 +73,7 @@ import { useMessage } from 'naive-ui'
 import draggable from 'vuedraggable'
 import api from '@/api'
 import PageHeader from '@/components/PageHeader.vue'
-import AksSaveBar from '@/components/form/AksSaveBar.vue'
+import JioSaveBar from '@/components/form/JioSaveBar.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'
@@ -162,13 +162,13 @@ onMounted(loadSettings)
 
 .float-settings__desc {
   font-size: 12px;
-  color: var(--aksrt-color-muted, #6F7A72);
+  color: var(--jio-color-muted, #6F7A72);
 }
 
 .float-settings__label {
   margin-left: 12px;
   font-size: 13px;
-  color: var(--aksrt-color-muted, #6F7A72);
+  color: var(--jio-color-muted, #6F7A72);
 }
 
 .float-settings__section {