feat(enemy): IPathAgent 增加 LastMoveObstructed/TryGetClosestReachable 契约

Assets/_Game/Scripts/Enemies/IPathAgent.cs

@@ -77,6 +77,15 @@ namespace BaseGames.Enemies
         /// </summary>
         bool ResolveStandablePoint(Vector2 target, out Vector2 standable);
 
+        /// <summary>
+        /// 上次寻路移动是否因目标不可达/被挡而受阻（走到最近可达点或原地停下，而非到达原目标）。
+        /// 供意图层(Locomotion)判断本次移动应否视为结算/推进。对新目标 RequestMoveTo 后复位。
+        /// </summary>
+        bool LastMoveObstructed { get; }
+
+        /// <summary>取上次寻路失败时算出的最近可达世界点（尽力贴近目标的点）。无则返回 false。</summary>
+        bool TryGetClosestReachable(out Vector2 worldPos);
+
         // ── 连接段事件 ──────────────────────────────────────────────────
         /// <summary>开始穿越连接段时触发（传入连接段类型）。</summary>
         event Action<NavLinkType> OnLinkStarted;
@@ -108,6 +117,8 @@ namespace BaseGames.Enemies
         public bool WalkToRandom()           => false;
         public bool WalkToRandomOnSegment()  => false;
         public bool ResolveStandablePoint(Vector2 target, out Vector2 standable) { standable = target; return false; }
+        public bool LastMoveObstructed       => false;
+        public bool TryGetClosestReachable(out Vector2 worldPos) { worldPos = Vector2.zero; return false; }
         public event Action<NavLinkType> OnLinkStarted  { add { } remove { } }
         public event Action<NavLinkType> OnLinkCompleted{ add { } remove { } }
         public event Action OnNavPathFailed              { add { } remove { } }