add auto-updater

src/services/app.ts

@@ -74,6 +74,7 @@ export class AppService extends EventEmitter<AppEventMap> {
       onRemoved: () => void;
     }
   >();
+  private stopPromise: Promise<void> | null = null;
 
   static async create(
     seed: string,
@@ -388,4 +389,17 @@ export class AppService extends EventEmitter<AppEventMap> {
       }),
     );
   }
+
+  /** Stop background services before the process exits or updates. */
+  async stop(): Promise<void> {
+    this.stopPromise ??= (async () => {
+      await Promise.allSettled([
+        this.rates.stop(),
+        this.electrum.stop?.() ?? Promise.resolve(),
+        ...this.invitations.map((invitation) => invitation.stop()),
+      ]);
+      await this.engine.stop();
+    })();
+    await this.stopPromise;
+  }
 }