Project updates/comments

Projects can have "updates" posted, which is a good way to track broad status. How about a `project comment` subcommand that can post comments, with an `--update` flag to make it an update?

<img width="533" height="144" alt="Image" src="https://github.com/user-attachments/assets/f4e3e12f-f096-4329-939d-bae08339ad59" />