trello.listBoardMembers returns stable member IDs for Add card member and checklist assignments.
automations/list-trello-members.automation.ts
board as an ID, short link, or URL. Optional second argument { account } defaults to the project binding. Returns Signal<TrelloMember[]> with IDs, names, usernames, initials, profile URLs, and avatar URLs. The action returns only members visible to the connected account.