feat: Implement DownDash ability and related systems

- Added DownDash ability with cooldown and speed configuration.
- Introduced DownDashState to handle down dashing mechanics, including gravity manipulation and animation playback.
- Updated PlayerMovement to support DownDash functionality.
- Enhanced PlayerStats to manage spring charge consumption and healing.
- Modified PlayerCombat and WeaponHitBoxInstance to support new hit confirmation events.
- Updated AbilityType to include new form types for character abilities.
- Improved Gizmos for better visualization of enemy detection and attack ranges.
- Added feedback systems for form switching in PlayerFeedback and IFeedbackPlayer.
- Refactored combat and movement states to accommodate new abilities and ensure smooth transitions.

Assets/_Game/Scripts/Enemies/EnemyFeedback.cs

@@ -45,6 +45,7 @@ namespace BaseGames.Enemies
         public void PlayFootstep()     { }
         public void TriggerPreset(string presetId) { }
         public void PlaySFXById(string sfxId) { }
+        public void PlayFormSwitch(int formIndex) { }  // 敌人无形态切换，空实现
 
         // ── EnemyBase 语义方法 ────────────────────────────────────────────
         /// <summary>受到伤害时调用（由 EnemyBase 触发）。</summary>