feat: 플레이어 다운 및 넉백 피격 반응 추가

- HitReactionController로 다운과 넉백 전용 로직을 분리
- 다운 시작, 루프, 회복 애니메이션과 DownEffect를 연결
- 행동 상태와 스킬 취소가 피격 반응과 연동되도록 정리
- 자동 검증 러너에 다운 및 넉백 검증을 추가

Assets/_Game/Scripts/Skills/Effects/DownEffect.cs

@@ -0,0 +1,42 @@
+using UnityEngine;
+
+using Colosseum.Player;
+
+namespace Colosseum.Skills.Effects
+{
+    /// <summary>
+    /// 대상에게 다운 상태를 적용하는 스킬 효과입니다.
+    /// </summary>
+    [CreateAssetMenu(fileName = "DownEffect", menuName = "Colosseum/Skills/Effects/Down")]
+    public class DownEffect : SkillEffect
+    {
+        [Header("Settings")]
+        [Tooltip("다운 지속 시간")]
+        [Min(0f)] [SerializeField] private float duration = 1f;
+
+        /// <summary>
+        /// 다운 지속 시간
+        /// </summary>
+        public float Duration => duration;
+
+        /// <summary>
+        /// 다운 효과를 적용합니다.
+        /// </summary>
+        protected override void ApplyEffect(GameObject source, GameObject target)
+        {
+            if (target == null)
+            {
+                Debug.LogWarning("[DownEffect] Target is null.");
+                return;
+            }
+
+            if (!target.TryGetComponent(out HitReactionController hitReactionController))
+            {
+                Debug.LogWarning($"[DownEffect] HitReactionController not found on target: {target.name}");
+                return;
+            }
+
+            hitReactionController.ApplyDown(duration);
+        }
+    }
+}

Assets/_Game/Scripts/Skills/Effects/DownEffect.cs.meta

@@ -0,0 +1,2 @@
+fileFormatVersion: 2
+guid: 41c96b54a96cdb84c9bda774775b0a1a

Assets/_Game/Scripts/Skills/Effects/KnockbackEffect.cs

@@ -1,5 +1,7 @@
 using UnityEngine;
 
+using Colosseum.Player;
+
 namespace Colosseum.Skills.Effects
 {
     /// <summary>
@@ -11,6 +13,7 @@ namespace Colosseum.Skills.Effects
         [Header("Knockback Settings")]
         [Min(0f)] [SerializeField] private float force = 5f;
         [SerializeField] private float upwardForce = 2f;
+        [Min(0.05f)] [SerializeField] private float duration = 0.2f;
 
         protected override void ApplyEffect(GameObject caster, GameObject target)
         {
@@ -18,13 +21,23 @@ namespace Colosseum.Skills.Effects
 
             Vector3 direction = target.transform.position - caster.transform.position;
             direction.y = 0f;
-            direction.Normalize();
+            if (direction.sqrMagnitude <= 0.0001f)
+                direction = caster.transform.forward;
+            else
+                direction.Normalize();
 
-            Vector3 knockback = direction * force + Vector3.up * upwardForce;
+            Vector3 knockbackVelocity = direction * force + Vector3.up * upwardForce;
 
-            // TODO: 실제 물리 시스템 연동
-            // if (target.TryGetComponent<Rigidbody>(out var rb))
-            //     rb.AddForce(knockback, ForceMode.Impulse);
+            if (target.TryGetComponent<HitReactionController>(out var hitReactionController))
+            {
+                hitReactionController.ApplyKnockback(knockbackVelocity, duration);
+                return;
+            }
+
+            if (target.TryGetComponent<PlayerMovement>(out var playerMovement))
+            {
+                playerMovement.ApplyForcedMovement(knockbackVelocity, duration);
+            }
         }
     }
 }