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/credits.css

@@ -100,19 +100,19 @@
 }
 
 /* ============ 签到 panel ============ */
-.aksrt-signin-status {
+.jio-signin-status {
 	margin: 0 0 16px;
 	color: var(--color-ink-2);
 	font-size: 14px;
 	line-height: 1.6;
 }
 
-.aksrt-signin-status strong {
+.jio-signin-status strong {
 	color: var(--color-primary);
 	font-weight: 700;
 }
 
-.aksrt-signin-tip {
+.jio-signin-tip {
 	margin: 0;
 	width: 100%;
 	color: var(--color-on-primary);
@@ -121,19 +121,19 @@
 }
 
 /* ============ 邀请 panel ============ */
-.aksrt-invite-desc {
+.jio-invite-desc {
 	margin: 0 0 16px;
 	color: var(--color-ink-2);
 	font-size: 14px;
 }
 
-.aksrt-invite-link-row {
+.jio-invite-link-row {
 	display: flex;
 	gap: 8px;
 	margin-bottom: 16px;
 }
 
-.aksrt-invite-link {
+.jio-invite-link {
 	flex: 1 1 auto;
 	height: 36px;
 	padding: 0 12px;
@@ -144,13 +144,13 @@
 	font: 500 13px/1 var(--font-mono, monospace);
 }
 
-.aksrt-invite-stats {
+.jio-invite-stats {
 	display: grid;
 	grid-template-columns: repeat(3, minmax(0, 1fr));
 	gap: 12px;
 }
 
-.aksrt-invite-stats > div {
+.jio-invite-stats > div {
 	display: flex;
 	flex-direction: column;
 	gap: 4px;
@@ -160,12 +160,12 @@
 	text-align: center;
 }
 
-.aksrt-invite-stats span {
+.jio-invite-stats span {
 	color: var(--color-ink-3);
 	font: 500 12px/1 var(--font-ui);
 }
 
-.aksrt-invite-stats strong {
+.jio-invite-stats strong {
 	color: var(--color-primary);
 	font: 700 22px/1 var(--font-ui);
 	font-variant-numeric: tabular-nums;
@@ -283,7 +283,7 @@
 }
 
 /* Configured paid-content tier icons. */
-.aksrt-vip-level-icon {
+.jio-vip-level-icon {
 	display: block;
 	width: auto;
 	height: 1.1em;