Fix metadata agent and player relative paths

furumi-agent/src/web/admin.html

@@ -323,7 +323,11 @@ tr:hover td { background: var(--bg-hover); }
 </div>
 
 <script>
-const API = '/api';
+// Derive API base from current page path so it works behind any reverse-proxy prefix
+// e.g. page at "/admin" or "/admin/" → API = "/admin/api"
+// e.g. page at "/" → API = "/api"
+const _base = location.pathname.replace(/\/+$/, '');
+const API = _base + '/api';
 let currentTab = 'queue';
 let currentFilter = null;