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/css/frontend/base.css

@@ -1,5 +1,5 @@
 /**
- * AKSRT Main v5 — 博客/个人站完整前端
+ * Jio Main v5 — 博客/个人站完整前端
  */
 
 /* 防止 hero 等使用 100vw / full-bleed 时产生横向滚动条 */
@@ -195,11 +195,11 @@ main.container,
  * All compact identity marks share one line-height baseline: VIP, level,
  * certification, and worn medals remain visually aligned in every surface.
  */
-.aksrt-user-level-badge,
-.aksrt-user-level-icon,
-.aksrt-identity-medal,
-.aksrt-identity-certification-icon,
-.aksrt-header-user-medal {
+.jio-user-level-badge,
+.jio-user-level-icon,
+.jio-identity-medal,
+.jio-identity-certification-icon,
+.jio-header-user-medal {
   display: inline-flex;
   align-items: center;
   justify-content: center;
@@ -211,16 +211,16 @@ main.container,
   flex: 0 0 auto;
   box-sizing: border-box;
 }
-.aksrt-user-level-badge {
+.jio-user-level-badge {
   padding: 0 .35em;
   font-size: .78em;
   line-height: 1.1;
   white-space: nowrap;
 }
 /* Comment context: keep all identity marks inside the compact author line. */
-.aksrt-identity-medal--comment,
-.aksrt-user-level-icon--comment,
-.aksrt-header-user-medal--comment {
+.jio-identity-medal--comment,
+.jio-user-level-icon--comment,
+.jio-header-user-medal--comment {
   height: 1em;
   vertical-align: -.12em;
 }
@@ -233,9 +233,9 @@ main.container,
 .article-avatar name,
 .article-avatar .name,
 .user-name,
-.aksrt-author-hero__name,
+.jio-author-hero__name,
 .uc-header__name,
-.aksrt-header-badges {
+.jio-header-badges {
   flex-wrap: nowrap;
   white-space: nowrap;
 }
@@ -251,21 +251,21 @@ main.container,
 .user-card.author .user-name > name > .follow {
   flex-shrink: 0;
 }
-.aksrt-author-hero__name,
+.jio-author-hero__name,
 .uc-header__name {
   display: inline-flex;
   align-items: center;
   gap: 4px;
 }
 
-.aksrt-author-hero__name-inner {
+.jio-author-hero__name-inner {
   display: inline-flex;
   align-items: center;
   gap: 4px;
   min-width: 0;
 }
 
-.aksrt-ip-geo-badge {
+.jio-ip-geo-badge {
   display: inline-flex;
   align-items: center;
   min-width: 0;