rework shop

backend/app/schemas/marathon.py

@@ -43,10 +43,10 @@ class ParticipantInfo(BaseModel):
     # Shop: coins and consumables status
     coins_earned: int = 0
     skips_used: int = 0
-    has_shield: bool = False
     has_active_boost: bool = False
-    boost_multiplier: float | None = None
-    boost_expires_at: datetime | None = None
+    has_lucky_dice: bool = False
+    lucky_dice_multiplier: float | None = None
+    can_undo: bool = False
 
     class Config:
         from_attributes = True