feat(enemy): 目标点吸附统一处理导航宽度,Waypoint 不再卡崖边

将"角色导航宽度"收口到导航执行层单一入口,意图层(Locomotion/AI)只递原始目标、不再感知身体尺寸:

- NavAgent 新增 TryGetStandablePointNear:把世界点映射到最近可行走段并按 endMargin 内缩两端(与 SetRandomDestinationOnCurrentSegment 同源)
- EnemyNavAgent 新增 ResolveStandablePoint,以 EnemyMovement.EdgeSafeMargin(半宽+落崖余量)为唯一宽度真源;加 _goalMapSearchRadius
- IPathAgent 暴露 ResolveStandablePoint;FlyingDirectNavigator 原样返回(飞行无崖沿约束),NullPathAgent 空实现
- EnemyLocomotion Waypoint 分支改用吸附后的可达点做移动与到达判定,修复路点摆在空中/崖外时永不到达而卡死;吸附失败显式报错暴露误配,不静默兜底

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

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

@@ -123,6 +123,13 @@ namespace BaseGames.Enemies.Navigation
         // 天然满足"就近游走"语义，直接复用。
         public bool WalkToRandomOnSegment() => WalkToRandom();
 
+        // 飞行单位直飞、无地面/崖沿/身体宽度约束——任意目标本就"站得住"，原样返回即可。
+        public bool ResolveStandablePoint(Vector2 target, out Vector2 standable)
+        {
+            standable = target;
+            return true;
+        }
+
         // ── 内部移动逻辑 ───────────────────────────────────────────────
         private void UpdateChase()
         {