Add support for the "Pie Rule" in the game.

[UO300731]

The Pie Rule is used to balance the advantage of the first move:

• Player 1 places the first move on the board.
• Player 2 then chooses whether to:
  a) Keep the roles (Player 1 continues), or
  b) Swap roles and become the first player.

Requirements:

• After the first move, the game must pause and allow Player 2 to choose.
• The UI must clearly present the choice to Player 2.
• If roles are swapped:
• Turn order must be updated accordingly.

Acceptance criteria:

• The second player is prompted after the first move.
• Selecting "swap" correctly changes roles and turn order.
• Selecting "keep" continues the game normally.
• The rule does not break existing game logic (winner detection, persistence, etc.).