List a workspace's members

This is the call behind the Users page: one request returns every member of the workspace, each with their contact details, the role they hold, and the spending policy that role gives them. People who have been invited but have not responded are not members yet, and are listed by GET /api/v1/get-pending-workspace-invites instead.

The response uses capitalised field names and mixes two ways of expressing a missing value, so read it carefully. FirstName, Surname, LastLogin, PhoneNumber, CyclePeriod, and CycleDay use the nullable wrapper described under payload conventions, where "Valid": false means no value is present and the value beside it should be ignored. TransactionLimit and AmountSpent are plain decimal strings, or null when the member has no spending policy. The UUID field is the member's user id, and it is what POST /api/v1/remove-user-from-workspace expects as user_uuid.