feat: port cms article detail layout into trade-pro (hero/body/related)

Task 10d: rewrite trade-pro article.html from the thin pro-article
skeleton to the cms news/[slug].astro design (pixel baseline
dist/hesupipe/en/news/<slug>/):

- hero reuses the 10c sf-tp-page-hero component (cover as bg image +
  brand-soft overlay) with the breadcrumb inside; the platform contract
  class .pro-article-hero stays on the hero section and the pro-base
  centered/giant-h1 skeleton is flattened by specificity in pro.css
- meta row (category pill - publish_date - author), rich-text body via
  body_copy with a cms rich-body typographic layer, divider, author
  card, next-story navigation
- related band below the content: More News side box (120px thumb rows,
  3 items, self and next-story excluded) + dark side CTA + back link,
  1fr+300px grid collapsing at 900/620
- date field is meta.fields.publish_date (blueprints post definition),
  rendered raw as YYYY-MM-DD
- new responsive rules live in the 10d media blocks appended at the end
  of pro.css to avoid the 10c source-order cascade trap; the 620 hero
  h1 compact size is re-declared at the same specificity because the
  10d no-media h1 reset (0,4,0) outranks the 10c 620 rule (0,3,0)
- tests: test_trade_pro_article_layout_structure builds a site with a
  cover/date/rich-body post plus 4 other posts and asserts hero/meta/
  body/author/next/related structure, .pro-article-hero presence, no
  bare arrow characters

Co-Authored-By: Claude Code <noreply@anthropic.com>

tests/test_theme_registry.py

@@ -336,6 +336,71 @@ def test_trade_pro_listing_layout_structure(factory):
     assert 'sf-tp-pagination' not in cases
 
 
+def test_trade_pro_article_layout_structure(factory):
+    # Task 10d：article.html 移植 cms 文章详情设计（news/[slug].astro，像素基准
+    # dist/hesupipe/en/news/<slug>/）后的结构契约。构建流（/preview/ HTTP）+
+    # 带 cover/publish_date/富文本正文的文章条目 + 4 条其他文章驱动断言：
+    # hero（.pro-article-hero 平台契约保留 + 封面底图 + 面包屑）、meta 行
+    # （分类胶囊 · 发布日期 · 作者）、富文本正文容器、作者卡、下一篇导航、
+    # More News 相关盒（不含自身、不含下一篇的去重列表）+ 侧栏 CTA + 返回；
+    # 交互箭头一律 SVG，无裸箭头字符。
+    import re
+    sid = site(factory)
+    assert factory.post(f'/api/factory/sites/{sid}/bootstrap').status_code == 200
+    made = factory.post(f'/api/sites/{sid}/entries', json={
+        'type': 'post', 'title': 'HDPE Pipe Export Standards Update', 'route': '/news/hdpe-standards/',
+        'cover': 'https://imgs.example/hdpe-cover.jpg', 'summary': 'Updated inspection rules for HDPE pipe exports.',
+        'body': '<p>Inspection requirements for <strong>HDPE</strong> pipe exports.</p><h2>Packaging</h2><p>Bundles are wrapped and strapped.</p>',
+        'meta': {'fields': {'category': 'Company News', 'publish_date': '2026-10-18', 'author': 'Trade Desk'}}})
+    assert made.status_code in (200, 201), made.text
+    for i in range(4):
+        r = factory.post(f'/api/sites/{sid}/entries', json={
+            'type': 'post', 'title': f'Worksite Report {i}', 'route': f'/news/worksite-{i}/',
+            'summary': f'Installation report from worksite {i}.'})
+        assert r.status_code in (200, 201), r.text
+    assert factory.put(f'/api/factory/sites/{sid}/theme', json={'theme': 'trade-pro', 'version': '1.0.0'}).status_code == 200
+    bid = factory.post(f'/api/sites/{sid}/builds', json={}).json()['version']
+    r = factory.get(f'/preview/{sid}/{bid}/news/hdpe-standards/')
+    assert r.status_code == 200, r.text[:400]
+    html = r.text
+    soup = BeautifulSoup(html, 'html.parser')
+    # hero：.pro-article-hero 契约保留（test_theme_pro_v3 对所有主题断言）+
+    # 封面作 hero 底图 + 面包屑（Home › News › 标题）+ 唯一 h1 + reveal
+    hero = soup.select_one('section.sf-tp-article-hero.pro-article-hero')
+    assert hero is not None
+    bg = hero.select_one('.sf-tp-page-hero-bg')
+    assert bg is not None and 'hdpe-cover.jpg' in bg.get('src', '')
+    assert hero.select_one('.sf-tp-breadcrumb a[href$="/news/"]')
+    assert hero.select_one('.sf-tp-page-hero-copy[data-reveal] h1')
+    assert len(soup.find_all('h1')) == 1
+    # meta 行：分类胶囊 + 发布日期（time）+ 作者字段
+    meta = soup.select_one('.sf-tp-article-meta')
+    assert meta is not None and 'Company News' in meta.get_text()
+    assert meta.find('time') is not None and '2026-10-18' in meta.find('time').get_text()
+    assert 'Trade Desk' in meta.get_text()
+    # 正文：body_copy 富文本容器（加粗与小节标题随文渲染）
+    body = soup.select_one('.sf-tp-article-body .pro-rich')
+    assert body is not None and 'HDPE' in body.get_text() and 'Packaging' in body.get_text()
+    # 分隔线 + 作者卡（首字母头像）
+    assert soup.select_one('.sf-tp-article-divider') is not None
+    assert soup.select_one('.sf-tp-article-author .sf-tp-article-avatar') is not None
+    # 下一篇导航：排除自身后的首条其他文章
+    nxt = soup.select_one('a.sf-tp-next-story')
+    assert nxt is not None and 'Worksite Report' in nxt.get_text()
+    # 相关阅读：More News 盒 3 条（其余文章），不含自身、不与下一篇重复
+    items = soup.select('.sf-tp-article-side-box a.sf-tp-article-side-item')
+    assert len(items) == 3
+    texts = [i.get_text() for i in items]
+    assert all('HDPE Pipe Export Standards' not in t for t in texts)
+    assert nxt.get('href') not in [i.get('href') for i in items]
+    assert items[0].select_one('.sf-tp-card-media img, .sf-tp-card-media .pro-art')
+    # 侧栏 CTA 指向联系页；返回链接回 /news/
+    assert soup.select_one('.sf-tp-article-side-cta a.sf-tp-btn[href$="/contact/"]')
+    assert soup.select_one('a.sf-tp-article-back[href$="/news/"]')
+    # 交互箭头一律 SVG（Task 9 契约），链接文本无裸箭头字符
+    assert not re.search(r'[←→↗↘⌕▾]', ''.join(a.get_text() for a in soup.find_all('a')))
+
+
 def test_frontend_entries_include_trade_pro():
     from pathlib import Path
     base = Path(__file__).resolve().parent.parent