fix: ResetRoom 시 BossRoom 레코드 정리

데디서버가 reset-room 호출 시 슬롯만 idle로 변경하고 BossRoom 레코드는
남아있어서 다음 입장 시 unique 제약 위반(Duplicate entry) 발생.
ResetRoom에서 해당 sessionName의 BossRoom 레코드도 함께 삭제.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

internal/bossraid/repository.go

@@ -206,6 +206,12 @@ func (r *Repository) ResetRoomSlot(sessionName string) error {
 	return result.Error
 }
 
+// DeleteRoomBySessionName removes BossRoom records for a given session name.
+// Used during ResetRoom to prevent duplicate session_name conflicts on next entry.
+func (r *Repository) DeleteRoomBySessionName(sessionName string) error {
+	return r.db.Where("session_name = ?", sessionName).Delete(&BossRoom{}).Error
+}
+
 // ResetStaleSlots clears instanceID for slots with stale heartbeats
 // and resets any active raids on those slots.
 func (r *Repository) ResetStaleSlots(threshold time.Time) (int64, error) {

internal/bossraid/service.go

@@ -473,9 +473,13 @@ func (s *Service) CheckStaleSlots() {
 	}
 }
 
-// ResetRoom resets a room slot back to idle.
+// ResetRoom resets a room slot back to idle and cleans up any lingering BossRoom records.
 // Called by the dedicated server after a raid ends and the runner is recycled.
 func (s *Service) ResetRoom(sessionName string) error {
+	// 완료/실패되지 않은 BossRoom 레코드 정리 (waiting/in_progress 상태)
+	if err := s.repo.DeleteRoomBySessionName(sessionName); err != nil {
+		log.Printf("BossRoom 레코드 정리 실패: %s: %v", sessionName, err)
+	}
 	return s.repo.ResetRoomSlot(sessionName)
 }