feat: extend GameHistory.Move to track promotionPiece

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

modules/core/src/main/scala/de/nowchess/chess/logic/GameHistory.scala

@@ -1,12 +1,14 @@
 package de.nowchess.chess.logic
 
 import de.nowchess.api.board.Square
+import de.nowchess.api.move.PromotionPiece
 
 /** A single move recorded in the game history. Distinct from api.move.Move which represents user intent. */
 case class HistoryMove(
   from: Square,
   to: Square,
-  castleSide: Option[CastleSide]
+  castleSide: Option[CastleSide],
+  promotionPiece: Option[PromotionPiece] = None
 )
 
 /** Complete game history: ordered list of moves. */
@@ -20,5 +22,13 @@ case class GameHistory(moves: List[HistoryMove] = List.empty):
   def addMove(from: Square, to: Square, castleSide: Option[CastleSide]): GameHistory =
     addMove(HistoryMove(from, to, castleSide))
 
+  def addMove(
+    from: Square,
+    to: Square,
+    castleSide: Option[CastleSide] = None,
+    promotionPiece: Option[PromotionPiece] = None
+  ): GameHistory =
+    addMove(HistoryMove(from, to, castleSide, promotionPiece))
+
 object GameHistory:
   val empty: GameHistory = GameHistory()

modules/core/src/test/scala/de/nowchess/chess/logic/GameHistoryTest.scala

@@ -1,6 +1,7 @@
 package de.nowchess.chess.logic
 
 import de.nowchess.api.board.*
+import de.nowchess.api.move.PromotionPiece
 import org.scalatest.funsuite.AnyFunSuite
 import org.scalatest.matchers.should.Matchers
 
@@ -39,3 +40,17 @@ class GameHistoryTest extends AnyFunSuite with Matchers:
     val history = GameHistory.empty.addMove(sq(File.E, Rank.R2), sq(File.E, Rank.R4))
     history.moves should have length 1
     history.moves.head.castleSide shouldBe None
+
+  test("Move with promotion records the promotion piece"):
+    val move = HistoryMove(sq(File.E, Rank.R7), sq(File.E, Rank.R8), None, Some(PromotionPiece.Queen))
+    move.promotionPiece should be (Some(PromotionPiece.Queen))
+
+  test("Normal move has no promotion piece"):
+    val move = HistoryMove(sq(File.E, Rank.R2), sq(File.E, Rank.R4), None, None)
+    move.promotionPiece should be (None)
+
+  test("addMove with promotion stores promotionPiece"):
+    val history = GameHistory.empty
+    val newHistory = history.addMove(sq(File.E, Rank.R7), sq(File.E, Rank.R8), None, Some(PromotionPiece.Rook))
+    newHistory.moves should have length 1
+    newHistory.moves.head.promotionPiece should be (Some(PromotionPiece.Rook))