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/user-card-checkin-badge-contract.test.cjs

@@ -8,7 +8,7 @@ const test = require('node:test')
 const root = path.resolve(__dirname, '..', '..')
 const read = (file) => fs.readFileSync(path.join(root, file), 'utf8')
 
-// Reference theme (zibll css/main.css): .jb-yellow sets --this-bg-b: #f59f54 and
+// Reference: .jb-yellow sets --this-bg-b: #f59f54 and
 // --this-bg: linear-gradient(135deg, #f59f54 10%, #ff6922 100%). build/public.min.css
 // is enqueued after main.min.css, so the legacy .jb-* compat layer in core/buttons.css
 // overrides main.css there; the two must agree or every .jb-yellow surface (the
@@ -49,7 +49,7 @@ test('the badge typography is pinned to the reference bootstrap body values', ()
   assert.notEqual(start, -1, 'missing the user-card img-badge adaptation rule')
   const block = main.slice(start, main.indexOf('}', start))
   assert.match(block, /line-height:\s*1\.42857143/)
-  // Reference body font stack (zibll bootstrap.min.css; zibll main.css does not
+  // Reference body font stack (bootstrap.min.css; main.css does not
   // override it), while Jio's reset imposes the modern --font-body stack.
   assert.match(block, /font-family:\s*"Helvetica Neue", Helvetica, Arial, sans-serif/)
   // The Jio html reset forces antialiased + optimizeLegibility; the badge