chore(branding): remove leftover upstream theme identifiers

The theme was renamed Zibll/子比 → AKSRT → Jio, but upstream branding
survived the sweeps in CSS classes, the SVG sprite prefix, a persisted
widget field ID, JS events, admin Vue class names, test infrastructure
and docblocks.

Renames:
- zib-widget / zib-widget-wrap / zib-slider → jio-widget-box /
  jio-widget-box-wrap / jio-slider-box (jio-widget is taken by the modern
  widget shell, jio-box-* by the card primitives)
- zib-partners-scroll + zps-* → jio-partners-scroll + jps-*
- zib-combo-info-card + zci-* → jio-combo-info-card + jci-*
- zibsvg- → jiosvg-, including the exported picker helpers and the
  fa-zibsvg- family-prefix guard
- zibpay_type → pay_type; the dual-read fallback in PostQuery collapses
  to a single key
- [zibajax="submit"] dropped (no PHP emitter); zib_ajax.success →
  jio_ajax.success
- aks-* admin Vue classes → jio-*
- zib_palette() → palette()

User-facing vendor traces are gone: the floating "more" button default no
longer ships a zibll.com link or 子比主题 marketing copy, the notice
widget ships no preset promo entries, and the four 官网教程 links are
removed from the post-list admin schema.

Test infrastructure renamed to neutral names (docker-compose.reference.yml,
Caddyfile, article-baseline.json, modern-widgets-contract.test.cjs) with
their DB/volume/env/slug identifiers following.

Kept intentionally, documented in tests/fixtures/README.md: the golden
fixture reference fingerprint (a SHA-256 record of an external directory,
read by validate-widget-golden / generate-widget-golden-fixture /
audit-widget-system), the doesNotMatch guards that prove the old tokens are
gone, and the reference theme's own meta key in the visual fixtures.

No backward-compat or data migration: saved widget configs holding old
icon keys or the old field ID silently lose them, per the project's
rewrite-over-compatibility rule.

Verified: 132/132 node contract tests, php tests/widget-system/run.php
(146 assertions), audit-admin-contracts, audit-psr4-paths and
validate-widget-golden all green; tracked bundles regenerated and in sync.

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

tests/widget-system/single-cover-height-contract.test.cjs

@@ -1,9 +1,9 @@
 'use strict';
 
 // 文章详情页顶部封面高度契约（对齐参考主题）：
-// 单图/多图(轮播)封面标题叠加封面，高度 = calc(比例% + 50px)（zibll .single-cover /
+// 单图/多图(轮播)封面标题叠加封面，高度 = calc(比例% + 50px)（.single-cover /
 // .single-cover-slide）；视频封面标题在下方 footer、无叠加，高度 = 裸比例%
-// （zibll .dplayer-scale-height）。
+// （视频封面高度计算契约）。
 
 const assert = require('node:assert/strict');
 const fs = require('node:fs');
@@ -36,8 +36,7 @@ test('single cover: video mode uses the bare ratio height like the reference dpl
     /single-cover--video imgbox-container" style="padding-bottom:<\?php echo esc_attr\(\$video_padding\); \?>%;"/,
     '视频封面必须输出裸比例高度（标题在下方 footer，无叠加补偿）'
   );
-  // +50px 是标题叠加封面的补偿量，仅单图/多图封面适用；视频封面
-  // 对齐参考主题 .dplayer-scale-height，不得继承该公式。
+  // +50px 是标题叠加封面的补偿量，仅单图/多图封面适用；视频封面不得继承该公式。
   assert.doesNotMatch(
     singleRender,
     /single-cover--video imgbox-container" style="padding-bottom:calc\(/,
@@ -140,7 +139,7 @@ test('video cover: footer breadcrumb sits in the reference flex row', () => {
   const breadcrumbCss = read('assets/css/frontend/breadcrumb.css');
   const coverCss = read('assets/css/frontend/single-post/cover.css');
 
-  // 对齐 zibll：footer 里面包屑直接位于 flex jsb at 行，无自造包装层。
+  // footer 里面包屑直接位于 flex jsb at 行，无自造包装层。
   assert.match(
     singleRender,
     /single-video-footer dplayer-featured">\s*\n\s*<div class="flex jsb at">\s*\n\s*<\?php echo \$crumbs;/,