feat(enemy): Wander 巡逻改为当前段内随机 + 按身体宽度内缩两端

修复地面单位 Wander 巡逻"走一小段就停"：
- 随机点从全图(GetRandomPointOnGraph)改为限定在 agent 当前所站的 NavSegment 上,
  不再跨越跳/落/拐角 NavLink,避免路径跨沟被崖边夹停或卡在过不去的 link。
- 段内随机 t 按"身体前缘安全余量(碰撞体半宽 + 悬崖检测前向偏移)"从两端各内缩,
  避免随机点落在角色宽度站不住的崖沿(WouldFallAhead 夹停、IsFollowingAPath 不复位→卡死)。
- NavAgent.SetRandomDestinationOnCurrentSegment(endMargin):段内采样+内缩(段过短退化到中点)
- EnemyMovement.EdgeSafeMargin:身体前缘安全余量
- IPathAgent.WalkToRandomOnSegment():EnemyNavAgent 传入 margin;飞行单位复用局部偏移;Null 返回 false

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Assets/PathBerserker2d/Scripts/PathBerserker2d/NavAgent/NavAgent.cs

@@ -594,6 +594,32 @@ namespace PathBerserker2d
             return PathTo(goal);
         }
 
+        // [项目新增] 段内随机游走：目标点限制在 agent 当前所站的这一条 NavSegment(cluster) 上，
+        // 不会跨越任何 NavLink(跳/落/拐角)，避免地面单位游走时被崖边夹停或卡在无法穿越的 link 处。
+        // 需要 agent 当前已映射到某条段上(currentMappedPosition 有效)，否则返回 false。
+        // 注意：一条 cluster 是一条直线段；被拐角/斜坡拆成多段的平台只会在当前这一段内游走。
+        /// <summary>
+        /// Start pathfinding to a random position ON THE SAME segment the agent currently stands on.
+        /// Never crosses a NavLink, so a ground unit stays on its current platform segment.
+        /// <paramref name="endMargin"/> insets the random range from BOTH segment ends (world units),
+        /// so the goal is never so close to the edge that a bodied agent can't stand there
+        /// (pass the agent's half-width + ledge-check margin). If the segment is shorter than
+        /// 2*endMargin the goal degenerates to the segment midpoint.
+        /// Returns false if the agent is not currently mapped to a segment.
+        /// </summary>
+        public bool SetRandomDestinationOnCurrentSegment(float endMargin = 0f)
+        {
+            if (currentMappedPosition.IsInvalid())
+                return false;
+
+            var cluster = currentMappedPosition.cluster;
+            float len = cluster.Length;
+            float m = Mathf.Clamp(endMargin, 0f, len * 0.5f); // 段太短 → 退化到中点
+            float t = UnityEngine.Random.Range(m, len - m);
+            Vector2 goal = cluster.owner.LocalToWorld.MultiplyPoint3x4(cluster.GetPositionAlongSegment(t));
+            return PathTo(goal);
+        }
+
 
         /// <summary>
         /// If you implement link traversal yourself, call this to complete a link traversal.

Assets/_Game/Scripts/Enemies/EnemyMovement.cs

@@ -262,6 +262,21 @@ namespace BaseGames.Enemies
                                       Vector2.down, _ledgeCheckDownDist, _groundMask);
         }
 
+        /// <summary>
+        /// 身体中心到"能站住的平台边缘最近点"的水平安全余量 = 碰撞体水平半宽 + 悬崖检测前向偏移。
+        /// WouldFallAhead 在"碰撞体前缘 + _ledgeCheckFwdOffset"处探地，故身体中心必须离平台边缘至少此距离，
+        /// 否则前缘探出崖沿被夹停。供 nav 段内随机游走把随机点从段两端各内缩此值，避免随机到身体站不住的崖沿点。
+        /// </summary>
+        public float EdgeSafeMargin
+        {
+            get
+            {
+                var col = GroundColliderOrSelf();
+                float halfWidth = col != null ? col.bounds.extents.x : 0f;
+                return halfWidth + Mathf.Max(0f, _ledgeCheckFwdOffset);
+            }
+        }
+
         private void WallAndLedgeCheck()
         {
             if (_wallCheckDist > 0f)

Assets/_Game/Scripts/Enemies/IPathAgent.cs

@@ -62,6 +62,13 @@ namespace BaseGames.Enemies
         /// <summary>移动到随机可到达点（巡逻 fallback）。</summary>
         bool WalkToRandom();
 
+        /// <summary>
+        /// 段内随机游走：随机点限制在 agent 当前所站的这一条导航段上，不跨越任何 NavLink(跳/落/拐角)。
+        /// 供 Wander 巡逻使用——地面单位只在当前平台段内来回，避免被崖边夹停或卡在过不去的 link 处。
+        /// 未映射到导航段(不在图上)时返回 false。
+        /// </summary>
+        bool WalkToRandomOnSegment();
+
         // ── 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;
@@ -91,6 +98,7 @@ namespace BaseGames.Enemies
         public Vector2 CurrentLinkEnd        => Vector2.zero;
         public bool CanReach(Vector2 _)      => false;
         public bool WalkToRandom()           => false;
+        public bool WalkToRandomOnSegment()  => false;
         public event Action<NavLinkType> OnLinkStarted  { add { } remove { } }
         public event Action<NavLinkType> OnLinkCompleted{ add { } remove { } }
         public event Action OnNavPathFailed              { add { } remove { } }

Assets/_Game/Scripts/Enemies/Navigation/EnemyLocomotion.cs

@@ -111,7 +111,9 @@ namespace BaseGames.Enemies
             switch (_patrolStrategy)
             {
                 case PatrolStrategy.Wander:
-                    if (_enemy.Nav != null && !_enemy.Nav.IsMoving) _enemy.Nav.WalkToRandom();
+                    // 段内随机游走：随机点限制在当前所站的导航段上，不跨越 NavLink，
+                    // 避免地面单位游走时被崖边夹停或卡在过不去的跳/落 link 处。
+                    if (_enemy.Nav != null && !_enemy.Nav.IsMoving) _enemy.Nav.WalkToRandomOnSegment();
                     break;
 
                 case PatrolStrategy.Pace: // 撞墙/悬崖翻向的来回踱步（速度驱动，不依赖 nav）

Assets/_Game/Scripts/Enemies/Navigation/EnemyNavAgent.cs

@@ -171,6 +171,11 @@ namespace BaseGames.Enemies.Navigation
 
         public bool WalkToRandom() => _navAgent?.SetRandomDestination() ?? false;
 
+        // 段内随机游走：按身体前缘安全余量内缩段两端，避免随机点落在角色宽度站不住的崖沿(WouldFallAhead 夹停)。
+        public bool WalkToRandomOnSegment()
+            => _navAgent?.SetRandomDestinationOnCurrentSegment(
+                   _enemyMovement != null ? _enemyMovement.EdgeSafeMargin : 0f) ?? false;
+
         public bool IsNearEdge()
         {
             var origin = (Vector2)transform.position;

Assets/_Game/Scripts/Enemies/Navigation/FlyingDirectNavigator.cs

@@ -119,6 +119,10 @@ namespace BaseGames.Enemies.Navigation
             return true;
         }
 
+        // 飞行单位无"导航段"概念，其 WalkToRandom 本就是当前位置的有界局部偏移，
+        // 天然满足"就近游走"语义，直接复用。
+        public bool WalkToRandomOnSegment() => WalkToRandom();
+
         // ── 内部移动逻辑 ───────────────────────────────────────────────
         private void UpdateChase()
         {