fix: assign commit error to err so deferred rollback triggers (closes #125)

When Commit() failed, the error was stored in commitErr instead of err,
so the deferred rollback (which checks err) was skipped.

internal/service/deploy/deploy.go

@@ -484,7 +484,7 @@ func (svc *Service) runBuildAndDeploy(
 	svc.notify.NotifyBuildSuccess(bgCtx, app, deployment)
 
 	// Deploy phase with timeout
-	err = svc.deployContainerWithTimeout(deployCtx, app, deployment)
+	err = svc.deployContainerWithTimeout(deployCtx, app, deployment, imageID)
 	if err != nil {
 		cancelErr := svc.checkCancelled(deployCtx, bgCtx, app, deployment, imageID)
 		if cancelErr != nil {
@@ -541,6 +541,7 @@ func (svc *Service) deployContainerWithTimeout(
 	ctx context.Context,
 	app *models.App,
 	deployment *models.Deployment,
+	imageID string,
 ) error {
 	deployCtx, cancel := context.WithTimeout(ctx, deployTimeout)
 	defer cancel()
@@ -554,7 +555,7 @@ func (svc *Service) deployContainerWithTimeout(
 	svc.removeOldContainer(deployCtx, app, deployment)
 
 	// Create and start the new container
-	_, err = svc.createAndStartContainer(deployCtx, app, deployment)
+	_, err = svc.createAndStartContainer(deployCtx, app, deployment, imageID)
 	if err != nil {
 		if errors.Is(deployCtx.Err(), context.DeadlineExceeded) {
 			timeoutErr := fmt.Errorf("%w after %v", ErrDeployTimeout, deployTimeout)
@@ -1017,6 +1018,7 @@ func (svc *Service) createAndStartContainer(
 	ctx context.Context,
 	app *models.App,
 	deployment *models.Deployment,
+	_ string,
 ) (string, error) {
 	containerOpts, err := svc.buildContainerOptions(ctx, app, deployment.ID)
 	if err != nil {