fix(aibox): 缩短 WebSocket 心跳间隔并补全直连页面心跳

前置代理（Nginx/CDN）的 proxy_read_timeout 约 20s，原 25s 心跳
无法在超时前到达，导致连接被代理切断。aibox.js 心跳从 25s 缩短至
10s；frontend.html 直连页面此前完全无心跳，新增 10s 应用层心跳。

aibox/frontend.html

@@ -1355,6 +1355,8 @@
             let reconnectAttempts = 0;
             const MAX_RECONNECT_ATTEMPTS = 5;
             let manualDisconnect = false;
+            let heartbeatTimer = null;
+            const HEARTBEAT_INTERVAL = 10000;
             
             function connectWebSocket() {
                 const wsUrl = document.getElementById('ws-url').value.trim();
@@ -1379,6 +1381,13 @@
                     reconnectAttempts = 0;
                     updateConnectionStatus(true);
                     showSystemMessage(`✅ WebSocket 连接成功！服务器: ${wsUrl}`);
+                    // 启动心跳保活，防止前置代理空闲超时断连
+                    if (heartbeatTimer) clearInterval(heartbeatTimer);
+                    heartbeatTimer = setInterval(() => {
+                        if (webSocket.readyState === WebSocket.OPEN) {
+                            webSocket.send(JSON.stringify({ type: 'ping' }));
+                        }
+                    }, HEARTBEAT_INTERVAL);
                 };
                 
                 webSocket.onmessage = (event) => {
@@ -1399,6 +1408,7 @@
                 
                 webSocket.onclose = (event) => {
                     console.log('WebSocket 断开连接:', event.code, event.reason);
+                    if (heartbeatTimer) { clearInterval(heartbeatTimer); heartbeatTimer = null; }
                     updateConnectionStatus(false);
                     
                     if (!manualDisconnect && reconnectAttempts < MAX_RECONNECT_ATTEMPTS) {

static/public/js/aibox.js

@@ -44,8 +44,8 @@ let ws = null;
 let manualClose = false;		/* 手动断开则抑制自动重连 */
 let reconnectDelay = RECONNECT_MIN;
 let reconnectTimer = null;
-let heartbeatTimer = null;		/* 心跳定时器，25s 发送 ping 保持 WS 连接 */
+let heartbeatTimer = null;		/* 心跳定时器，10s 发送 ping 保持 WS 连接 */
-const HEARTBEAT_INTERVAL = 25000;	/* 心跳间隔（< gateway 30s 空闲超时） */
+const HEARTBEAT_INTERVAL = 10000;	/* 心跳间隔：需低于前置代理（Nginx/CDN）的 proxy_read_timeout */
 
 function startHeartbeat() {
 	stopHeartbeat();