fix: Restore myBetPlaced variable that was incorrectly removed

- Re-added myBetPlaced variable which is used for betting phase UI rendering

panel/src/games/blackjack/BlackjackGame.tsx

@@ -398,6 +398,7 @@ export function BlackjackGame({ state, myPlayerId, isSpectator, onAction, player
     }, [players]);
 
     const mySeat = view.seats[myPlayerId];
+    const myBetPlaced = mySeat?.hasBet ?? false;
 
     // Determine who can sit (spectators during betting phase)
     const canSitDown = isSpectator && isBetting && view.turnOrder.length < 6;