feat(chinese-chess): 实现中国象棋核心逻辑和基本功能

- 抽象出 ChessCore 类，包含游戏初始化、行棋逻辑、悔棋等功能
- 重构 Player 类，优化行棋和记录逻辑
- 更新 ChessBoard 和 ChessPiece 类，适应新逻辑
- 移除冗余代码，提高代码可读性和可维护性

Scripts/Src/ChineseChess/ChineseChess.cs

@@ -0,0 +1,154 @@
+using Vector2 = Godot.Vector2;
+using System;
+using System.Collections;
+namespace ChineseChess;
+
+class ChessCore {
+    public enum Mode {
+        SingleMode,
+        MultiMode,
+        DebugMode,
+    };
+
+    public enum TurnsSideType {
+        Red,
+        Black,
+    };
+
+    public enum PlayerSideType {
+        Self,
+        Opponent,
+        Any,
+    };
+
+    private TurnsSideType sideType = TurnsSideType.Red;
+    private readonly TurnsSideType selfSide;
+    public readonly VirtualBoard board = new(9, 10);
+    private readonly Player playerSelf;
+    private readonly Player playerOpponent;
+    private readonly MoveRecords<VirtualPiece> moveRecords;
+    public EventHandler<VirtualBoard.MoveEventArgs> OnMove;
+
+    public ChessCore(Mode mode, TurnsSideType selfSide) {
+        this.selfSide = selfSide;
+
+        playerSelf = new(board, Player.PlayerType.Human);
+        playerOpponent = new(board, Player.PlayerType.Human);
+
+        playerSelf.OnMove += (sender, args) => {
+            moveRecords.AddRecord(board.GetPiece(args.To), board.GetPiece(args.From),
+                args.To, args.From);
+        };
+        playerOpponent.OnMove += (sender, args) => {
+            moveRecords.AddRecord(board.GetPiece(args.To), board.GetPiece(args.From),
+                args.To, args.From);
+        };
+        
+		moveRecords = new MoveRecords<VirtualPiece>(
+        onAddRecordCallback: (newNode, oldNode, newPos, oldPos) => {
+            playerSelf.SelectedClear();
+            playerOpponent.SelectedClear();
+        },
+        onUndoRecordCallback: (newNode, oldNode, newPos, oldPos) => {
+			// GD.Print("Undo: ", newNode, "->", oldNode, ":", newPos, "->", oldPos);
+			VirtualPiece newPiece = newNode;
+			VirtualPiece oldPiece = oldNode;
+			board.MovePiece(newPos, oldPos);
+			if (newPiece != null) {
+				board.InsertPiece(newPiece, newPos);
+			}
+		});
+
+        switch (mode) {
+            case Mode.SingleMode:
+                break;
+            case Mode.MultiMode:
+                break;
+            default:
+            case Mode.DebugMode:
+                throw new NotImplementedException();
+        }
+
+    }
+
+    public void InitGame() {
+        ArrayList blackPart = InitOnePartPieces(TurnsSideType.Black, new[] {
+            ("车", 0, 0), ("马", 1, 0), ("象", 2, 0),
+            ("士", 3, 0), ("将", 4, 0), ("士", 5, 0),
+            ("象", 6, 0), ("马", 7, 0), ("车", 8, 0),
+            ("炮", 1, 2), ("炮", 7, 2),
+            ("卒", 0, 3), ("卒", 2, 3), ("卒", 4, 3), ("卒", 6, 3), ("卒", 8, 3)
+            });
+
+        ArrayList redPart = InitOnePartPieces(TurnsSideType.Red, new[] {
+            ("车", 0, -0), ("马", 1, -0), ("象", 2, -0),
+            ("士", 3, -0), ("将", 4, -0), ("士", 5, -0),
+            ("象", 6, -0), ("马", 7, -0), ("车", 8, -0),
+            ("炮", 1, -2), ("炮", 7, -2),
+            ("卒", 0, -3), ("卒", 2, -3), ("卒", 4, -3), ("卒", 6, -3), ("卒", 8, -3)
+            });
+        if (selfSide == TurnsSideType.Red) {
+            playerSelf.SetAllowedPieces(redPart);
+            playerOpponent.SetAllowedPieces(blackPart);
+        } else {
+            playerSelf.SetAllowedPieces(blackPart);
+            playerOpponent.SetAllowedPieces(redPart);
+        }
+    }
+
+    private ArrayList InitOnePartPieces(TurnsSideType side, (string label, int x, int y)[] positions) {
+        ArrayList list = new();
+        foreach (var (label, x, y) in positions) {
+            // FIXME: use a better way to initialize pieces
+            Vector2 pos = new(x, y + (TurnsSideType.Red == side ? 9 : 0));
+            VirtualPiece piece = new(label, pos);
+            list.Add(piece);
+            board.InsertPiece(piece, pos);
+        }
+        return list;
+    }
+
+    public void OnPosClicked(Vector2 pos, PlayerSideType clickedSide = PlayerSideType.Any) {
+        if (sideType == selfSide) {
+            playerSelf.CanMove = true;
+            playerOpponent.CanMove = false;
+        } else {
+            playerSelf.CanMove = false;
+            playerOpponent.CanMove = true;
+        }
+
+        switch (clickedSide) {
+            case PlayerSideType.Any:
+                playerSelf.HandleBoardPosClick(pos);
+                playerOpponent.HandleBoardPosClick(pos);
+                break;
+            case PlayerSideType.Self:
+                playerSelf.HandleBoardPosClick(pos);
+                break;
+            case PlayerSideType.Opponent:
+                playerOpponent.HandleBoardPosClick(pos);
+                break;
+        }
+
+        sideType = moveRecords.Count() % 2 == 0 ? TurnsSideType.Red : TurnsSideType.Black;
+    }
+
+    public TurnsSideType GetTurnsType() {
+        sideType = moveRecords.Count() % 2 == 0 ? TurnsSideType.Red : TurnsSideType.Black;
+        return sideType;
+    }
+
+    public void Undo() {
+		playerSelf.SelectedClear();
+        playerOpponent.SelectedClear();
+		moveRecords.Undo();
+	}
+
+	public void ReInit() {
+        playerSelf.SelectedClear();
+        playerOpponent.SelectedClear();
+		moveRecords.Clear();
+		board.Clear();
+        InitGame();
+	}
+}