Bereinige Agent-Shutdown fuer bereits gestoppte Contexts

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

player/agent/internal/app/app.go

@@ -88,8 +88,16 @@ func (a *App) Run(ctx context.Context) error {
 		return fmt.Errorf("screen id is required")
 	}
 
+	select {
+	case <-ctx.Done():
+		a.mu.Lock()
+		a.status = StatusStopped
+		a.mu.Unlock()
+		return nil
+	default:
+	}
+
 	a.mu.Lock()
-	a.status = StatusRunning
 	a.startedAt = a.now()
 	a.mu.Unlock()
 
@@ -101,6 +109,9 @@ func (a *App) Run(ctx context.Context) error {
 		a.Config.HeartbeatEvery,
 	)
 	a.emitHeartbeat()
+	a.mu.Lock()
+	a.status = StatusRunning
+	a.mu.Unlock()
 
 	ticker := time.NewTicker(time.Duration(a.Config.HeartbeatEvery) * time.Second)
 	defer ticker.Stop()

player/agent/internal/app/app_test.go

@@ -107,3 +107,31 @@ func TestAppSnapshotIncludesConfiguredTargets(t *testing.T) {
 		t.Fatalf("HeartbeatEvery = %d, want %d", got, want)
 	}
 }
+
+func TestAppRunWithCanceledContextDoesNotLogConfiguredOrHeartbeat(t *testing.T) {
+	var logBuffer bytes.Buffer
+	application := newApp(config.Config{
+		ScreenID:       "screen-canceled",
+		ServerBaseURL:  "http://127.0.0.1:8080",
+		MQTTBroker:     "tcp://127.0.0.1:1883",
+		HeartbeatEvery: 5,
+	}, log.New(&logBuffer, "", 0), time.Now)
+
+	ctx, cancel := context.WithCancel(context.Background())
+	cancel()
+
+	if err := application.Run(ctx); err != nil {
+		t.Fatalf("Run() error = %v", err)
+	}
+
+	if got, want := application.Snapshot().Status, StatusStopped; got != want {
+		t.Fatalf("final status = %q, want %q", got, want)
+	}
+
+	logs := logBuffer.String()
+	for _, needle := range []string{"event=agent_configured", "event=heartbeat_tick"} {
+		if strings.Contains(logs, needle) {
+			t.Fatalf("logs unexpectedly contain %q: %s", needle, logs)
+		}
+	}
+}