[Feature Request] Save & Reopen Project for Editing

Great work on OpenScreen 👏 really useful tool.

One limitation I noticed:
After exporting a video, there’s no way to reopen the project to make changes.

It would be very helpful to:

- Save a project
- Reopen it later
- Edit zooms, annotations, trims, etc. without re-recording

Even a basic project save/load feature would greatly improve the workflow.

Thanks for the awesome open-source project 🙌