upgrade: adopt V8.21.3 (V8.13→8.21.3: P5 SFTP/S3, P6 multilingual, editor overhaul, enterprise hardening)

Overlay ~150 upstream items onto our V8.12 base, preserving trade-pro
theme, registry tests, and design docs. Re-applied our patch set
(discovery/env_for/blocks.css/type-mapping/theme_color/frontend entries,
test_theme_pro_v3 mods) — all anchors survived upstream evolution.

New platform enhancement (fixes upgrade-introduced regression):
multilingual.site_locale now honors settings_json.locale, plus
PUT /api/i18n/sites/{id}/locale — standalone English sites get
<html lang='en'> under the V8.15 locale-rewrite pipeline.

compose: adopt V8.21.3 (image 8.21.3-dev.1, /api/ready probes, MySQL/S3
env) with project name pinned to siteforge-v8-10 (data volumes).

Tests: 356 passed / 11 failed — all 11 confirmed pre-existing in
pristine V8.21.3 on this host (10 upstream Windows env + our build test
now green after locale fix). Patch registry updated in plan doc.

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

app/templates/production-v8.html

@@ -4,7 +4,7 @@
 
 [hidden]{display:none!important}.tool-switch{display:flex;flex-wrap:wrap;gap:9px;background:#fff;padding:12px;margin:18px 0 0;border-radius:12px;border:1px solid #e1e8f1}.tool-btn{background:#f6f8fc;color:#50627c;border-color:transparent;padding:11px 14px}.tool-btn.active{background:#e8f0ff;color:#174ea7;border:1px solid #a5c5f5}.tool-help{font-size:12px;color:#64748b;margin:12px 5px 16px}.advanced-layout{grid-template-columns:minmax(0,1fr)}.advanced-layout>.panel{width:100%}.nav a:first-child{border:1px solid #7793bd;padding:9px 11px;border-radius:7px;background:#fff1}@media(max-width:720px){.tool-switch{gap:5px}.tool-btn{padding:9px 11px}}
 </style><link rel="stylesheet" href="/ui/professional-ui.css"><script defer src="/ui/professional-ui.js"></script></head><body data-sf-page="production">
-<header><div><h1>SiteForge · 网站生产控制台 <span style="font-size:11px;color:#acd5ff">V8.11 · 高级工具</span></h1><small>整站模板 · 数据批次导入 · 可审计回滚 · 静态构建</small></div><div class="nav"><a href="/">返回网站工作台</a><a href="/factory-studio">页面编辑器</a><a href="/theme-gallery">主题中心</a><a href="/operations">任务中心</a></div></header>
+<header><div><h1>SiteForge · 网站生产控制台 <span style="font-size:11px;color:#acd5ff">V8.21 · 高级工具</span></h1><small>整站模板 · 数据批次导入 · 可审计回滚 · 静态构建</small></div><div class="nav"><a href="/">返回网站工作台</a><a href="/factory-studio">页面编辑器</a><a href="/theme-gallery">主题中心</a><a href="/operations">任务中心</a></div></header>
 <main>
  <div class="panel"><div class="row" style="justify-content:space-between"><div><h2>选择要操作的网站</h2><div class="muted">所有批次、模板和构建记录均按网站隔离；新网站可先在网站工作台创建。</div></div><select id="site" style="max-width:410px" aria-label="选择网站"></select></div></div>
  <section class="kpi"><article><span class="muted">当前网站</span><strong id="siteName">—</strong></article><article><span class="muted">内容记录</span><strong id="entryCount">—</strong></article><article><span class="muted">导入批次</span><strong id="batchCount">—</strong></article></section>
@@ -51,6 +51,11 @@
      <button id="wpCancel" class="danger">取消迁移</button>
      <button id="wpReload">刷新状态</button><button id="wpAudit">对比最新构建的 URL/SEO</button>
    </div>
+   <div class="row" style="margin-top:12px;align-items:flex-end">
+     <div style="flex:2;min-width:250px"><label for="wpPreflightFile">V8.20 离线 WXR 兼容预检（不会导入或修改内容）</label><input id="wpPreflightFile" type="file" accept=".xml,application/xml"></div>
+     <button id="wpPreflight" class="primary">检查旧 URL / Elementor / ACF / 动态功能</button>
+   </div>
+   <pre id="wpPreflightResult" class="message">上传有权迁移的 WordPress WXR 文件，可检查路径冲突、复杂字段和动态功能。预检不等于迁移完成。</pre>
    <pre id="wpResult" class="message">选择站点并新建迁移会话。每页请求独立保存检查点；采集完成后可明确审核 URL、SEO、缺失内容。</pre>
  </section>
 
@@ -128,6 +133,7 @@ $('preflight').onclick=()=>applyTemplate(false);$('apply').onclick=()=>applyTemp
 $('build').onclick=async()=>{try{show('buildResult',await api(`/api/sites/${current()}/builds`,'POST',{mirror_images:false}))}catch(e){show('buildResult','错误：'+e.message)}};
 async function loadWpSessions(){try{if(!current())return;const result=await api(`/api/migrations/sites/${current()}/wordpress/sessions`);const select=$('wpSession');const chosen=select.value;select.replaceChildren(...result.items.map(s=>opt(s.id,`${s.origin} · ${s.state} · ${s.fetched} 条`)));if(result.items.some(s=>s.id===chosen))select.value=chosen;if(select.value){const item=await api(`/api/migrations/sites/${current()}/wordpress/sessions/${select.value}`);show('wpResult',item)}}catch(e){show('wpResult','查询错误：'+e.message)}}
 async function wpAction(action){const sid=$('wpSession').value;if(!sid)throw Error('请先创建迁移会话');return api(`/api/migrations/sites/${current()}/wordpress/sessions/${sid}/${action}`,'POST',{})}
+$('wpPreflight').onclick=async()=>{try{if(!current())throw Error('请先选择网站');const file=$('wpPreflightFile').files[0];if(!file)throw Error('请选择 WordPress WXR XML 文件');const form=new FormData();form.append('file',file);const result=await api(`/api/migrations/sites/${current()}/wordpress/wxr-preflight`,'POST',form);show('wpPreflightResult',result)}catch(e){show('wpPreflightResult','兼容性预检失败：'+e.message)}};
 $('wpCreate').onclick=async()=>{try{const data=await api(`/api/migrations/sites/${current()}/wordpress/sessions`,'POST',{origin:$('wpOrigin').value,max_items:Number($('wpLimit').value)});await loadWpSessions();$('wpSession').value=data.id;show('wpResult',data)}catch(e){show('wpResult','错误：'+e.message)}};
 let wpAutoRunning=false;
 $('wpAuto').onclick=async()=>{if(wpAutoRunning)return;wpAutoRunning=true;let count=0;try{while(wpAutoRunning&&count<200){const r=await wpAction('advance');show('wpResult',r);count++;if(['ready','completed','cancelled','limit_reached'].includes(r.state))break;await new Promise(done=>setTimeout(done,350))}await loadWpSessions()}catch(e){show('wpResult','暂停：'+e.message)}finally{wpAutoRunning=false}};