At 8 PM Eastern on Wednesday, if no non-cancelled mission starts on that
week's upcoming Friday, post once in #side-ops pinging the Community
Zeus role (DISCORD_COMMUNITY_ZEUS_ROLE_ID, or the role resolved by
name): the slot is open, hosting is welcome, and otherwise the slot
stays empty or Jason hosts it himself. Dedup uses a stable per-Friday
timestamp token scanned from recent channel messages, so no DB state.
When a non-superuser later claims the slot the notice is edited to
credit them; a cancelled or deleted claim reverts the notice, and a
between-polls claim swap re-credits the new claimant.