feat(participation): isolate opted-out combat

design/user-stories/us-011-inform-and-manage-participation.md

@@ -20,6 +20,11 @@ As a **player**, I want to understand my status and control my eligibility so th
 - [x] A player cannot opt back in until seven days have elapsed by default.
 - [x] The opt-out duration is configurable, uses unpaused elapsed time, and survives restart.
 - [x] Participation commands are idempotent and clearly report current status and remaining time.
+- [x] While the event is running, damage is cancelled when the Tyrant or an Assassin, Fixer, or Tamer attacks an opted-out player.
+- [x] While the event is running, damage is cancelled when an opted-out player attacks the Tyrant or an Assassin, Fixer, or Tamer.
+- [x] Cancelled attackers are told that the target has chosen not to take part in the Tyrant event.
+- [x] Protection covers direct player attacks and player-fired projectiles without changing unrelated combat.
+- [x] Participation combat protection does not apply while the event is paused or not started.
 
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