add linked card attribute to effect

src/model/card.py

@@ -13,6 +13,7 @@ class Effect(Serializable):
     mutex: List["Effect"]
     effect_type: Optional[EffectType] = None
     times: Optional[EffectTimes] = None
+    card: Optional["Card"] = None
 
     def __init__(
         self,
@@ -39,6 +40,7 @@ class Effect(Serializable):
         return super().serialize() | {
             "sub_effects": [effect.uuid for effect in self.sub_effects],
             "mutex": [effect.uuid for effect in self.mutex],
+            "card": self.card.uuid,
         }