A Mission owner can pause or resume a Mission according to the current server-side lifecycle rules.
Cancellation is allowed only while a Mission is active or paused. It is blocked while submitted participations are still waiting for owner review.
When a Mission is cancelled, claimed but unsubmitted participations expire. Already verified work and rewards are preserved.
Any refund is based on unfilled required slots and is added as a new Credit ledger entry instead of rewriting earlier history.
