refactor: manage monitor via gateway hooks

plugin/hooks/gateway-stop.ts

@@ -0,0 +1,23 @@
+import { stopManagedMonitor } from '../core/managed-monitor';
+
+export function registerGatewayStopHook(api: any, deps: {
+  logger: any;
+  getMetaPushInterval: () => ReturnType<typeof setInterval> | null;
+  clearMetaPushInterval: () => void;
+  stopCalendarScheduler: () => void;
+}) {
+  const { logger, getMetaPushInterval, clearMetaPushInterval, stopCalendarScheduler } = deps;
+
+  api.on('gateway_stop', () => {
+    logger.info('HarborForge plugin stopping');
+
+    const handle = getMetaPushInterval();
+    if (handle) {
+      clearInterval(handle);
+      clearMetaPushInterval();
+    }
+
+    stopCalendarScheduler();
+    stopManagedMonitor(logger);
+  });
+}