Update on-call channel topic with today's on-call owner

You lose time when on-call ownership in your channel is stale, causing unclear routing and delayed triage. This updates the topic so stakeholders see the current responder each weekday morning.

Overview

Outdated on-call info creates confusion and slows incident triage. Refreshing the team channel topic each weekday morning gives engineering managers and on-call engineers a single source of truth, enabling faster routing and action within minutes. Deploying this eliminates guesswork during handoffs and keeps stakeholders aligned ahead of incidents.