fix(backend): 商品公开页移除「在 App 中查看」链接

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JJ1g8XV1YhhmHRzhwWEW7o

backend/internal/handler/templates/public_product.html

@@ -187,7 +187,7 @@
 {{end}}
   <footer class="foot">
     <div class="foot-rule">◆</div>
-    <div>Powered by <a class="brand" href="https://jiu.51yanmei.com">岩美科技</a>{{if .AppURL}} · <a href="{{.AppURL}}">在 App 中查看</a>{{end}}</div>
+    <div>Powered by <a class="brand" href="https://jiu.51yanmei.com">岩美科技</a></div>
     <div class="icp"><a href="https://beian.miit.gov.cn" target="_blank" rel="noopener">京ICP备2026039814号</a></div>
   </footer>
 </div>