Add host connection status check endpoint and UI indicator

- Implement handle_connection_status API to test host port reachability
- Display Host:Up/Down status in the UI

src/static/webssh.js

@@ -10,6 +10,7 @@ let maxUploadSize = localStorage.getItem('maxUploadSize') ? parseInt(localStorag
 let apiBaseUrl = window.location.origin;
 let backendWsPort = null;
 let backendWsHost = null;
+let hostStatusTimer = null;
 
 // Use the frontend proxy so the browser does not need direct access to the backend port.
 function getWsUrl() {
@@ -41,6 +42,8 @@ async function loadSavedConnections() {
         if (!conn.terminalBuffer) conn.terminalBuffer = [];
       });
       renderConnectionList();
+      refreshHostStatuses();
+      startHostStatusPolling();
       if (connections.length > 0) {
         term.writeln(`[Loaded ${connections.length} connections from server]`);
       }
@@ -454,6 +457,9 @@ function renderConnectionList() {
         <span class="connection-status ${conn.connected ? 'connected' : 'disconnected'}"></span>
         ${conn.username}@${conn.host}:${conn.port}
       </div>
+      <div class="host-status ${conn.hostStatus === true ? 'up' : conn.hostStatus === false ? 'down' : 'checking'}">
+        Host: ${conn.hostStatus === true ? 'Up' : conn.hostStatus === false ? 'Down' : 'Checking...'}
+      </div>
       <div class="connection-actions" onclick="event.stopPropagation()">
         ${conn.connected 
           ? `<button class="btn-small btn-disconnect" onclick="disconnectConnection('${conn.id}')">Disconnect</button>`
@@ -467,6 +473,40 @@ function renderConnectionList() {
   });
 }
 
+async function refreshHostStatuses() {
+  if (!authToken || connections.length === 0) return;
+
+  connections.forEach(conn => { conn.hostStatus = null; });
+  renderConnectionList();
+
+  try {
+    const response = await fetch(`${apiBaseUrl}/api/connections/status`, {
+      method: 'POST',
+      headers: {
+        'Content-Type': 'application/json',
+        'Authorization': `Bearer ${authToken}`
+      },
+      body: JSON.stringify({ ids: connections.map(conn => conn.id) })
+    });
+    if (!response.ok) return;
+
+    const data = await response.json();
+    connections.forEach(conn => {
+      if (Object.prototype.hasOwnProperty.call(data.statuses || {}, conn.id)) {
+        conn.hostStatus = data.statuses[conn.id];
+      }
+    });
+    renderConnectionList();
+  } catch (e) {
+    console.warn('Failed to refresh host statuses:', e);
+  }
+}
+
+function startHostStatusPolling() {
+  if (hostStatusTimer) clearInterval(hostStatusTimer);
+  hostStatusTimer = setInterval(refreshHostStatuses, 30000);
+}
+
 function selectConnection(id) {
   currentConnectionId = id;
   const conn = getCurrentConnection();