Allow promo codes to only be redeemed once

rc_core/src/persist/user/traits.rs

@@ -85,6 +85,7 @@ pub trait User<C>: ChatUser + SocialUser + LobbyUser + MultiplayerUser + Singlep
     fn current_game_event_setter(&self) -> Box<dyn GameEventSetter>;
     async fn apply_purchase(&self, action: &crate::persist::config::ShopAction) -> Result<PurchaseResult, polariton_server::operations::SimpleOpError>;
     async fn currency_debit(&self, ty: CurrencyType, to_sub: u64) -> Result<(), polariton_server::operations::SimpleOpError>;
+    async fn mark_code_redeemed(&self, code: String) -> Result<bool, polariton_server::operations::SimpleOpError>;
 }
 
 #[async_trait::async_trait]