feat: 注册准则阅读控制 + Footer 合规信息

准则阅读（三层控制）：
- registration.show_guidelines — 弹窗/复选框模式
- registration.force_guidelines — 是否强制倒计时+滚动
- registration.guidelines_timer — 倒计时秒数

Footer 合规（8 字段，空值不显示，链接纯手写）：
- site.operator_name / site.icp_number / site.icp_license
- site.police_number / site.wenwangwen / site.algorithm_filing
- site.privacy_url / site.terms_url
- 新增 safeHTML 模板函数输出不转义 HTML

templates/MetaLab-2026/html/layout/footer.html

@@ -1,6 +1,19 @@
 <footer>
     <div class="container footer-content">
         <p class="copyright">&copy; {{.CopyrightStart}}-{{.CurrentYear}} {{.SiteName}}{{if .Framework}} | {{.Framework}}{{end}}{{if .CanAccessAdmin}} | <a href="/admin">管理面板</a>{{end}}</p>
+        {{$hasCompliance := or .OperatorName .ICPNumber .ICPLicense .PoliceNumber .WenWangWen .AlgorithmFiling .PrivacyURL .TermsURL}}
+        {{if $hasCompliance}}
+        <p class="footer-compliance">
+            {{if .PrivacyURL}}{{if ne .PrivacyURL ""}}{{safeHTML .PrivacyURL}}{{end}}{{end}}
+            {{if .TermsURL}}{{if ne .TermsURL ""}} | {{safeHTML .TermsURL}}{{end}}{{end}}
+            {{if .OperatorName}}{{if ne .OperatorName ""}} | {{.OperatorName}}{{end}}{{end}}
+            {{if .ICPNumber}}{{if ne .ICPNumber ""}} | {{safeHTML .ICPNumber}}{{end}}{{end}}
+            {{if .ICPLicense}}{{if ne .ICPLicense ""}} | {{safeHTML .ICPLicense}}{{end}}{{end}}
+            {{if .PoliceNumber}}{{if ne .PoliceNumber ""}} | {{safeHTML .PoliceNumber}}{{end}}{{end}}
+            {{if .WenWangWen}}{{if ne .WenWangWen ""}} | {{safeHTML .WenWangWen}}{{end}}{{end}}
+            {{if .AlgorithmFiling}}{{if ne .AlgorithmFiling ""}} | {{safeHTML .AlgorithmFiling}}{{end}}{{end}}
+        </p>
+        {{end}}
     </div>
 </footer>
 <script src="/static/js/common.js?v={{assetV "/static/js/common.js"}}" nonce="{{.CSPNonce}}"></script>