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/posts-toc-css-contract.test.cjs

@@ -18,7 +18,7 @@ test('article TOC widget uses the shared reference tree styles, not posts-navs p
     '.posts-nav-lists li.active::before',
   ]) assert.ok(mainCss.includes(selector), `main.css retains reference tree rule ${selector}`);
   assert.match(mainCss, /\.posts-nav-box\s*\{[^}]*font-family:\s*inherit;[^}]*font-size:\s*14px;[^}]*line-height:\s*1\.42857143;/s);
-  const panel = mainCss.match(/\.posts-nav-box \.zib-widget\s*\{([^}]*)\}/)?.[1] || '';
+  const panel = mainCss.match(/\.posts-nav-box \.jio-widget-box\s*\{([^}]*)\}/)?.[1] || '';
   for (const declaration of [
     /background-color:\s*var\(--main-bg-color\)/,
     /padding:\s*15px/,
@@ -31,7 +31,7 @@ test('article TOC widget uses the shared reference tree styles, not posts-navs p
 test('mobile TOC panel and its collapse control remain styled and accessible', () => {
   const mainCss = read('assets/css/main.css');
 
-  assert.match(mainCss, /\.mobile-navbar \.posts-nav-box \.zib-widget\s*\{[^}]*background:\s*var\(--muted-border-color\);[^}]*box-shadow:\s*none;/s);
+  assert.match(mainCss, /\.mobile-navbar \.posts-nav-box \.jio-widget-box\s*\{[^}]*background:\s*var\(--muted-border-color\);[^}]*box-shadow:\s*none;/s);
   assert.match(mainCss, /\.posts-nav-lists \.nav-toggle-collapse\s*\{[^}]*border:\s*0;[^}]*background:\s*transparent;/s);
   assert.match(mainCss, /\.posts-nav-box \.posts-nav-lists :where\(a, \.nav-toggle-collapse\):focus-visible/);
   assert.match(mainCss, /@media \(prefers-reduced-motion: reduce\)[\s\S]*?\.posts-nav-lists \.nav-toggle-collapse \{\s*transition:\s*none;/);