List a newsletter's automations

The newsletter's automations, most recently written first. Needs sending: read.

Archived ones are left out unless ?status=archived asks for them. Deleting an automation archives it rather than removing it, because the runs underneath it are the record of what was emailed to whom, so without that default the answer to "what automations do I have" would be a history.

Each row is an AutomationSummary, which is the automation without its graph. A send_email step holds a whole email body, so a page of automations with their graphs inlined would be a newsletter's worth of prose; step_count is enough to tell an empty draft from a built sequence, and GET /automations/{automation} has the graph.