fix: harden service websocket reconnect flows

Stabilize the service console and callback-host websocket paths so idle disconnects and mid-task client drops no longer wedge task execution or spam repeated commands.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/service_console_html_test.rs

@@ -12,6 +12,12 @@ fn service_console_html_stays_on_service_ws_boundary() {
 
     assert!(source.contains("ws://127.0.0.1:42321"));
     assert!(source.contains("submit_task"));
+    assert!(source.contains("addEventListener(\"close\""));
+    assert!(source.contains("setTimeout(() => connectOrDisconnectService(true)"));
+    assert!(source.contains("connectTimeoutTimer"));
+    assert!(source.contains("lastHeartbeatAt"));
+    assert!(source.contains("heartbeat missed, forcing reconnect"));
+    assert!(source.contains("service websocket connect timed out"));
     assert!(!source.contains("/sgclaw/browser-helper.html"));
     assert!(!source.contains("/sgclaw/callback/ready"));
     assert!(!source.contains("/sgclaw/callback/events"));