feat: add network module and service for TCP latency measurement and proxy performance

web/static/js/app.js

@@ -296,6 +296,7 @@ async function checkServerLatencies(nodes) {
         try {
             const res = await fetch('/ping-target', {
                 method: 'POST',
+                headers: { 'Content-Type': 'application/json' },
                 body: JSON.stringify({ server: node.server, port: node.server_port || 443 })
             });
             const data = await res.json();