I own several Next.js boilerplates that handle front end and backend, but not the research, PRD and validation steps ProductOS does. Trying to see where ProductOS fits:
1. Can a build start from my own existing repo or boilerplate, or does it always generate from scratch?
2. Can I save a custom template / stack and reuse it for all new projects?
3. Can I use only the research + PRD + design stages, export them, and build elsewhere? Do those stages use credits the same way building does?