refactor(chess): 重构象棋程序基础结构,使用Nullable重构核心代码

- 更新了多个文件的代码结构和类型定义，提高了代码的健壮性和可维护性
- 优化了事件处理、棋子管理和移动逻辑，为后续功能扩展打下坚实基础
- 修复了一些潜在的空指针异常问题，提高了程序的稳定性
- 修复部分bug

Test/src/TestVector.cs

@@ -0,0 +1,93 @@
+using Vector;
+namespace Test;
+public class TestsVector
+{
+    [SetUp]
+    public void Setup()
+    {
+    }
+
+    [Test]
+    public void Test1()
+    {
+        Assert.Pass();
+    }
+
+    [Test]
+    public void TestVector2I_Constructors()
+    {
+        // Arrange & Act
+        var v1 = new Vector2I();
+        var v2 = new Vector2I(1, 2);
+        var v3 = new Vector2I(v2);
+
+        // Assert
+        Assert.That(v1.X, Is.EqualTo(0));
+        Assert.That(v1.Y, Is.EqualTo(0));
+        Assert.That(v2.X, Is.EqualTo(1));
+        Assert.That(v2.Y, Is.EqualTo(2));
+        Assert.That(v3.X, Is.EqualTo(1));
+        Assert.That(v3.Y, Is.EqualTo(2));
+    }
+
+    [Test]
+    public void TestVector2I_Operators()
+    {
+        // Arrange
+        var v1 = new Vector2I(1, 2);
+        var v2 = new Vector2I(3, 4);
+
+        // Act
+        var v3 = v1 + v2;
+        var v4 = v1 - v2;
+        var v5 = v1 * v2;
+
+        // Assert
+        Assert.That(v3, Is.EqualTo(new Vector2I(4, 6)));
+        Assert.That(v4, Is.EqualTo(new Vector2I(-2, -2)));
+        Assert.That(v5, Is.EqualTo(new Vector2I(3, 8)));
+    }
+
+    [Test]
+    public void TestTrans2DI_Constructors()
+    {
+        // Arrange & Act
+        var t1 = new Trans2DI();
+        var t2 = new Trans2DI(new Vector2I(1, 0), new Vector2I(0, 1), new Vector2I(0, 0));
+        var t3 = new Trans2DI(t2);
+        var t4 = new Trans2DI(1, 0, 0, 1, 0, 0);
+
+        // Assert
+        Assert.That(t1.XAxis, Is.EqualTo(new Vector2I(1, 0)));
+        Assert.That(t1.YAxis, Is.EqualTo(new Vector2I(0, 1)));
+        Assert.That(t1.Origin, Is.EqualTo(new Vector2I(0, 0)));
+
+        Assert.That(t2.XAxis, Is.EqualTo(new Vector2I(1, 0)));
+        Assert.That(t2.YAxis, Is.EqualTo(new Vector2I(0, 1)));
+        Assert.That(t2.Origin, Is.EqualTo(new Vector2I(0, 0)));
+
+        Assert.That(t3.XAxis, Is.EqualTo(new Vector2I(1, 0)));
+        Assert.That(t3.YAxis, Is.EqualTo(new Vector2I(0, 1)));
+        Assert.That(t3.Origin, Is.EqualTo(new Vector2I(0, 0)));
+
+        Assert.That(t4.XAxis, Is.EqualTo(new Vector2I(1, 0)));
+        Assert.That(t4.YAxis, Is.EqualTo(new Vector2I(0, 1)));
+        Assert.That(t4.Origin, Is.EqualTo(new Vector2I(0, 0)));
+    }
+
+    [Test]
+    public void TestTrans2DI_Operators()
+    {
+        // Arrange
+        var t1 = new Trans2DI(new Vector2I(1, 0), new Vector2I(0, 1), new Vector2I(1, 2));
+        var v1 = new Vector2I(3, 4);
+
+        // Act
+        var v2 = t1 * v1;
+        var v3 = v1 * t1;
+
+        // Assert
+        Assert.That(v2, Is.EqualTo(new Vector2I(4, 6)));
+        Assert.That(v3, Is.EqualTo(new Vector2I(2, 2)));
+    }
+}