unixTimestamp vs timestamp

[ncpenke]

Thank you for the awesome work on this and frames.js! We're adding support for frames to our platform, and looking to confirm to this spec. One question we had was around the timestamp. In the @open-frames/types package, the field is timestamp, but in the spec here it's unixTimestamp. Can we just use timestamp for all protocols, and interpret it based on the client protocol i.e. can this spec be revisited to change unixTimestamp to timestamp?

Thank you!