feat(security): add trusted proxies and abuse event cleanup

- Add `WARPBOX_TRUSTED_PROXIES` configuration to restrict accepted forwarded client IP headers to specific proxy IPs/CIDRs, securing client IP resolution.
- Integrate `BanService` into the background cleanup job to automatically purge expired abuse and ban evidence events.
- Update documentation with reverse proxy security guidelines and a production systemd deployment guide.

backend/templates/pages/admin_settings.html

@@ -9,6 +9,8 @@
       <a class="sidebar-link" href="/admin/users">{{template "icon-user-circle" .}}<span>Users</span></a>
       <a class="sidebar-link is-active" href="/admin/settings">{{template "icon-settings" .}}<span>Settings</span></a>
       <a class="sidebar-link" href="/admin/storage">{{template "icon-database" .}}<span>Storage</span></a>
+      <a class="sidebar-link" href="/admin/logs">{{template "icon-database" .}}<span>Logs</span></a>
+      <a class="sidebar-link" href="/admin/bans">{{template "icon-settings" .}}<span>Bans</span></a>
     </nav>
     <hr class="sidebar-sep">
     <nav class="sidebar-nav">