Send daily belated shift alerts to managers channel

Late shift requests pile up overnight, leaving coordinators without a consolidated view of yesterday's requests. Receive one daily digest in ops so coordinators fix gaps before the morning handoff.

Overview

When late shift requests sit unresolved overnight, morning operations lose visibility and scramble to reassign staff. This flow centralizes yesterday's overdue assignments into a single, formatted ops-channel digest every morning, so coordinators can close gaps before the handoff.