feat(quests): add issuer quest cancellation

knowledge/user-stories/us-006-cancel-an-owned-quest.md

@@ -2,7 +2,7 @@
 type: User Story
 title: "US-006: Cancel an owned quest"
 description: Let an issuer cancel an active quest and reclaim its escrowed reward safely.
-status: backlog
+status: done
 ---
 
 # US-006: Cancel an owned quest
@@ -11,15 +11,15 @@ As a **quest issuer**, I want to cancel my active quest so that I can reclaim th
 
 ## Acceptance criteria
 
-- [ ] An issuer can cancel their own active quest through any registered board.
-- [ ] A player cannot cancel a quest issued by another player.
-- [ ] Completed, cancelled, and expired quests cannot be cancelled.
-- [ ] Cancellation removes the quest from active listings and converts its exact escrowed reward into a claim for the issuer.
-- [ ] The reward is not inserted directly into the issuer's inventory during cancellation.
-- [ ] When player commands are enabled, `/quests cancel <quest>` provides equivalent behavior and only autocompletes the player's cancellable quest identifiers.
-- [ ] Cancellation and simultaneous completion are serialized so items cannot be duplicated or lost.
-- [ ] Persistence failure leaves the quest active and its reward escrowed.
-- [ ] Automated tests verify ownership, state validation, claim creation, autocomplete, rollback, and completion races.
+- [x] An issuer can cancel their own active quest through any registered board.
+- [x] A player cannot cancel a quest issued by another player.
+- [x] Completed, cancelled, and expired quests cannot be cancelled.
+- [x] Cancellation removes the quest from active listings and converts its exact escrowed reward into a claim for the issuer.
+- [x] The reward is not inserted directly into the issuer's inventory during cancellation.
+- [x] When player commands are enabled, `/quests cancel <quest>` provides equivalent behavior and only autocompletes the player's cancellable quest identifiers.
+- [x] Cancellation and simultaneous completion are serialized so items cannot be duplicated or lost.
+- [x] Persistence failure leaves the quest active and its reward escrowed.
+- [x] Automated tests verify ownership, state validation, claim creation, autocomplete, rollback, and completion races.
 
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