feat(update): add core auto-updater and dry-run preview

src/gateway/server-close.ts

@@ -15,6 +15,7 @@ export function createGatewayCloseHandler(params: {
   pluginServices: PluginServicesHandle | null;
   cron: { stop: () => void };
   heartbeatRunner: HeartbeatRunner;
+  updateCheckStop?: (() => void) | null;
   nodePresenceTimers: Map<string, ReturnType<typeof setInterval>>;
   broadcast: (event: string, payload: unknown, opts?: { dropIfSlow?: boolean }) => void;
   tickInterval: ReturnType<typeof setInterval>;
@@ -70,6 +71,11 @@ export function createGatewayCloseHandler(params: {
     await stopGmailWatcher();
     params.cron.stop();
     params.heartbeatRunner.stop();
+    try {
+      params.updateCheckStop?.();
+    } catch {
+      /* ignore */
+    }
     for (const timer of params.nodePresenceTimers.values()) {
       clearInterval(timer);
     }