Log FCM service account env value at startup.

Add a notification-service startup log to print FCM_SERVICE_ACCOUNT_KEY for runtime verification during push notification troubleshooting.

Co-authored-by: Cursor <cursoragent@cursor.com>

internal/services/notification/service.go

@@ -68,6 +68,10 @@ func New(
 		config:         cfg,
 	}
 
+	mongoLogger.Info("FCM_SERVICE_ACCOUNT_KEY value at startup",
+		zap.String("fcm_service_account_key", cfg.FCMServiceAccountKey),
+	)
+
 	// Initialize FCM client if service account key is provided
 	if cfg.FCMServiceAccountKey != "" {
 		if err := svc.initFCMClient(); err != nil {