List a project's members

Who has been invited to a project. Read this to confirm an invitation actually landed, and to see the current list before changing it with PUT /projects/update — a membership change made through the API is readable back here, by the same identity that made it. Members exist only on a PERSONAL-scoped project. An organization project is visible to the whole organization by definition and carries no member rows at all, so it answers an empty list rather than naming your colleagues. You must already be able to reach the project: you created it (your organization's projects and your own personal ones), or you hold an invitation to it. Anything else is a 404, including a project id that exists but is not yours to see. An invitation is re-checked on read rather than trusted. A member who has since left the project creator's organization no longer resolves, so a known project id does not keep returning a roster after the invitation has stopped meaning anything.