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>

tests/widget-system/repeater-row-key-stability.test.cjs

@@ -1,10 +1,10 @@
 'use strict';
 
 /**
- * AksField 的 group / repeater 行身份稳定性契约。
+ * JioField 的 group / repeater 行身份稳定性契约。
  *
  * 背景：inline 展开模式用 vuedraggable 渲染行，vuedraggable 的 computeNodes 会把
- * `node.key = getKey(element)`，而行 key 由 AksField 的 repeaterDragKey 提供。服务端
+ * `node.key = getKey(element)`，而行 key 由 JioField 的 repeaterDragKey 提供。服务端
  * 历史行没有 _id，key 来自以「对象身份」为键的 WeakMap。
  *
  * 关键坑：行数据是 reactive 的。updateRepeaterItem 一旦把行展开成一个新对象，渲染时
@@ -20,7 +20,7 @@ const test = require('node:test');
 
 const root = path.resolve(__dirname, '..', '..');
 const fieldVue = fs.readFileSync(
-  path.join(root, 'assets', 'admin', 'src', 'components', 'form', 'AksField.vue'),
+  path.join(root, 'assets', 'admin', 'src', 'components', 'form', 'JioField.vue'),
   'utf8'
 );
 
@@ -47,7 +47,7 @@ function reactiveOf(value) {
 /** 取一整行声明（WeakMap / 种子计数器都没有花括号体）。 */
 function declaration(source, marker) {
   const start = source.indexOf(marker);
-  assert.notStrictEqual(start, -1, `AksField.vue 缺少声明: ${marker}`);
+  assert.notStrictEqual(start, -1, `JioField.vue 缺少声明: ${marker}`);
   const end = source.indexOf('\n', start);
   return source.slice(start, end === -1 ? undefined : end);
 }
@@ -55,7 +55,7 @@ function declaration(source, marker) {
 /** 按花括号配平切出一个顶层函数（这些函数体内没有字符串/注释里的孤立花括号）。 */
 function functionBlock(source, marker) {
   const start = source.indexOf(marker);
-  assert.notStrictEqual(start, -1, `AksField.vue 缺少函数: ${marker}`);
+  assert.notStrictEqual(start, -1, `JioField.vue 缺少函数: ${marker}`);
   const open = source.indexOf('{', start);
   assert.notStrictEqual(open, -1, `函数没有函数体: ${marker}`);
   let depth = 0;