feat(state): 添加状态机系统核心功能实现

- 实现了基础状态机StateMachine类，支持状态注册、切换和生命周期管理
- 创建了上下文感知状态机ContextAwareStateMachine，能够感知架构上下文并发送状态变更事件
- 定义了IState和IStateMachine抽象接口，规范状态和状态机的行为契约
- 添加了StateChangedEvent事件类，用于通知状态变更
- 实现了游戏专用状态机GameStateMachine，提供类型安全的状态检查和获取功能

GFramework.Core.Abstractions/state/IState.cs

@@ -0,0 +1,26 @@
+namespace GFramework.Core.Abstractions.state;
+
+/// <summary>
+/// 状态机状态接口，定义了状态的基本行为和转换规则
+/// </summary>
+public interface IState
+{
+    /// <summary>
+    /// 当状态被激活进入时调用
+    /// </summary>
+    /// <param name="from">从哪个状态转换而来，可能为null表示初始状态</param>
+    void OnEnter(IState? from);
+
+    /// <summary>
+    /// 当状态退出时调用
+    /// </summary>
+    /// <param name="to">将要转换到的目标状态，可能为null表示结束状态</param>
+    void OnExit(IState? to);
+
+    /// <summary>
+    /// 判断当前状态是否可以转换到目标状态
+    /// </summary>
+    /// <param name="target">目标状态</param>
+    /// <returns>如果可以转换则返回true，否则返回false</returns>
+    bool CanTransitionTo(IState target);
+}

GFramework.Core.Abstractions/state/IStateMachine.cs

@@ -0,0 +1,37 @@
+namespace GFramework.Core.Abstractions.state;
+
+/// <summary>
+/// 状态机接口，用于管理状态的注册、切换和验证
+/// </summary>
+public interface IStateMachine
+{
+    /// <summary>
+    /// 获取当前激活的状态
+    /// </summary>
+    IState? Current { get; }
+
+    /// <summary>
+    /// 注册一个状态到状态机中
+    /// </summary>
+    /// <param name="state">要注册的状态实例</param>
+    void Register(IState state);
+
+    /// <summary>
+    /// 从状态机中注销指定类型的状态
+    /// </summary>
+    /// <typeparam name="T">要注销的状态类型，必须实现IState接口</typeparam>
+    void Unregister<T>() where T : IState;
+
+    /// <summary>
+    /// 检查是否可以切换到指定类型的状态
+    /// </summary>
+    /// <typeparam name="T">目标状态类型，必须实现IState接口</typeparam>
+    /// <returns>如果可以切换则返回true，否则返回false</returns>
+    bool CanChangeTo<T>() where T : IState;
+
+    /// <summary>
+    /// 切换到指定类型的状态
+    /// </summary>
+    /// <typeparam name="T">要切换到的状态类型，必须实现IState接口</typeparam>
+    void ChangeTo<T>() where T : IState;
+}

GFramework.Core/state/ContextAwareStateMachine.cs

@@ -0,0 +1,82 @@
+using GFramework.Core.Abstractions.architecture;
+using GFramework.Core.Abstractions.enums;
+using GFramework.Core.Abstractions.rule;
+using GFramework.Core.Abstractions.state;
+using GFramework.Core.Abstractions.system;
+using GFramework.Core.extensions;
+
+namespace GFramework.Core.state;
+
+/// <summary>
+/// 上下文感知状态机，继承自StateMachine并实现ISystem接口
+/// 该状态机能够感知架构上下文，并在状态切换时发送状态变更事件
+/// </summary>
+public class ContextAwareStateMachine : StateMachine, ISystem
+{
+    /// <summary>
+    /// 架构上下文对象，用于提供系统运行所需的上下文信息
+    /// </summary>
+    protected IArchitectureContext Context = null!;
+
+    /// <summary>
+    /// 设置架构上下文的方法
+    /// </summary>
+    /// <param name="context">要设置的架构上下文对象</param>
+    public void SetContext(IArchitectureContext context)
+    {
+        Context = context;
+    }
+
+    /// <summary>
+    /// 获取当前架构上下文的方法
+    /// </summary>
+    /// <returns>当前的架构上下文对象</returns>
+    public IArchitectureContext GetContext()
+    {
+        return Context;
+    }
+
+    /// <summary>
+    /// 处理架构生命周期阶段的方法
+    /// </summary>
+    /// <param name="phase">当前所处的架构生命周期阶段</param>
+    public virtual void OnArchitecturePhase(ArchitecturePhase phase)
+    {
+    }
+
+    /// <summary>
+    /// 初始化方法，在系统启动时调用
+    /// 遍历所有状态实例，为实现了IContextAware接口的状态设置上下文
+    /// </summary>
+    public virtual void Init()
+    {
+        foreach (var state in States.Values.OfType<IContextAware>())
+        {
+            state.SetContext(Context);
+        }
+    }
+
+    /// <summary>
+    /// 销毁方法，在系统关闭时调用
+    /// </summary>
+    public virtual void Destroy()
+    {
+    }
+
+    /// <summary>
+    /// 内部状态切换方法，重写基类方法以添加状态变更事件通知功能
+    /// </summary>
+    /// <param name="next">要切换到的下一个状态</param>
+    protected override void ChangeInternal(IState next)
+    {
+        var old = Current;
+        base.ChangeInternal(next);
+
+        // 发送状态变更事件，通知监听者状态已发生改变
+        this.SendEvent(new StateChangedEvent
+        {
+            OldState = old,
+            NewState = Current
+        });
+    }
+}

GFramework.Core/state/StateChangedEvent.cs

@@ -0,0 +1,19 @@
+using GFramework.Core.Abstractions.state;
+
+namespace GFramework.Core.state;
+
+/// <summary>
+/// 表示状态变更事件的数据类
+/// </summary>
+public sealed class StateChangedEvent
+{
+    /// <summary>
+    /// 获取变更前的旧状态
+    /// </summary>
+    public IState? OldState { get; init; }
+
+    /// <summary>
+    /// 获取变更后的新状态
+    /// </summary>
+    public IState? NewState { get; init; }
+}

GFramework.Core/state/StateMachine.cs

@@ -0,0 +1,87 @@
+using GFramework.Core.Abstractions.state;
+
+namespace GFramework.Core.state;
+
+/// <summary>
+/// 状态机实现类，用于管理状态的注册、切换和生命周期
+/// </summary>
+public class StateMachine : IStateMachine
+{
+    /// <summary>
+    /// 存储所有已注册状态的字典，键为状态类型，值为状态实例
+    /// </summary>
+    protected readonly Dictionary<Type, IState> States = new();
+
+    /// <summary>
+    /// 获取当前激活的状态
+    /// </summary>
+    public IState? Current { get; private set; }
+
+    /// <summary>
+    /// 注册一个状态到状态机中
+    /// </summary>
+    /// <param name="state">要注册的状态实例</param>
+    public void Register(IState state)
+        => States[state.GetType()] = state;
+
+    /// <summary>
+    /// 从状态机中注销指定类型的状态
+    /// </summary>
+    /// <typeparam name="T">要注销的状态类型</typeparam>
+    public void Unregister<T>() where T : IState
+    {
+        var type = typeof(T);
+        if (!States.TryGetValue(type, out var state)) return;
+
+        // 如果当前状态是要注销的状态，则先执行退出逻辑
+        if (Current == state)
+        {
+            Current.OnExit(null);
+            Current = null;
+        }
+
+        States.Remove(type);
+    }
+
+    /// <summary>
+    /// 检查是否可以切换到指定类型的状态
+    /// </summary>
+    /// <typeparam name="T">目标状态类型</typeparam>
+    /// <returns>如果可以切换则返回true，否则返回false</returns>
+    public bool CanChangeTo<T>() where T : IState
+    {
+        if (!States.TryGetValue(typeof(T), out var target))
+            return false;
+
+        return Current?.CanTransitionTo(target) ?? true;
+    }
+
+    /// <summary>
+    /// 切换到指定类型的状态
+    /// </summary>
+    /// <typeparam name="T">目标状态类型</typeparam>
+    /// <exception cref="InvalidOperationException">当目标状态未注册时抛出</exception>
+    public void ChangeTo<T>() where T : IState
+    {
+        if (!States.TryGetValue(typeof(T), out var target))
+            throw new InvalidOperationException("State not registered.");
+
+        ChangeInternal(target);
+    }
+
+    /// <summary>
+    /// 内部状态切换方法，处理状态切换的核心逻辑
+    /// </summary>
+    /// <param name="next">下一个状态实例</param>
+    protected virtual void ChangeInternal(IState next)
+    {
+        if (Current == next) return;
+        if (Current != null && !Current.CanTransitionTo(next)) return;
+
+        var old = Current;
+        old?.OnExit(next);
+
+        Current = next;
+        Current.OnEnter(old);
+    }
+}

GFramework.Game/state/GameStateMachine.cs

@@ -0,0 +1,26 @@
+using GFramework.Core.Abstractions.state;
+using GFramework.Core.state;
+
+namespace GFramework.Game.state;
+
+/// <summary>
+/// 游戏状态机类，继承自ContextAwareStateMachine，用于管理游戏中的各种状态
+/// </summary>
+public sealed class GameStateMachine : ContextAwareStateMachine
+{
+    /// <summary>
+    /// 检查当前状态是否为指定类型的状态
+    /// </summary>
+    /// <typeparam name="T">要检查的状态类型，必须实现IState接口</typeparam>
+    /// <returns>如果当前状态是指定类型则返回true，否则返回false</returns>
+    public bool IsIn<T>() where T : IState
+        => Current is T;
+
+    /// <summary>
+    /// 获取当前状态的实例，如果当前状态是指定类型则进行类型转换
+    /// </summary>
+    /// <typeparam name="T">要获取的状态类型，必须是引用类型并实现IState接口</typeparam>
+    /// <returns>如果当前状态是指定类型则返回转换后的实例，否则返回null</returns>
+    public T? Get<T>() where T : class, IState
+        => Current as T;
+}