Now that you have your code managed through VSTS or GitHub, you'll need a way to manage your SharePoint Framework customizations in SharePoint. Once again, there are multiple approaches to this task and you're free to choose the one that most fits your own development workflow and experience.
As all the SharePoint Framework solutions are packaged with Gulp to a separate package, it's very easy to move one or more files to SharePoint for testing and deploying to production. Each SharePoint Framework package is a file with the extension .sppkg, and they work distantly, similarly to SharePoint add-ins.
A centralized approach for this would imply you would use the application catalog, which is a special type of SharePoint site that includes the mechanisms for storing add-ins and SharePoint Framework Packages, and then deploying those through your SharePoint via site collections.
You can have multiple solutions in the application...