feat(client): implement exponential backoff retry for network errors

backend/cmd/api/main.go

@@ -79,6 +79,7 @@ func run(logger *slog.Logger) error {
 		httpClient,
 		config.ZarinHubEndpoint,
 		tokenManager,
+		config.ZarinHubRetries,
 	)
 	cardService := service.NewCardService(zarinHubClient)
 	auditRepository := repository.NewAuditRepository(db)