Announce daily on-call captain and update team roster

Your on-call calendar events aren't relayed, so captain assignments are missed, leaving coverage unclear. It posts the captain announcement and updates the roster so coverage is visible at shift start.

Overview

Stop relying on manual handoffs at shift change — this flow announces today's captain in-channel and records the assignment automatically. The team sees coverage in real time and the roster updates immediately at event start, reducing last-minute confusion at shift start.