Get current user's prompts

Returns the system prompts that apply to the caller in their active organization, in the order desktops append them to OpenWork's instructions: prompts for everyone, then each of the caller's teams' prompts by team name, then prompts assigned to the caller. Desktops read it with their provider sync. Requires the Prompts feature; answers 404 while it is off, and desktops then add no prompts.