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/Feedback/IFeedbackPlayer.cs

@@ -44,6 +44,10 @@ namespace BaseGames.Feedback
 
         /// <summary>通过 sfxId 触发单次音效（不带任何摄像机/振动反馈）。</summary>
         void PlaySFXById(string sfxId);
+
+        // ── 形态切换 ──────────────────────────────────────────────────────────────
+        /// <summary>切换到指定形态时播放对应反馈（音效 + 粒子 + 震屏等）。formIndex 对应 FormType 枚举值。</summary>
+        void PlayFormSwitch(int formIndex);
     }
 
     /// <summary>命中力度。</summary>
@@ -67,6 +71,7 @@ namespace BaseGames.Feedback
         public void PlayFootstep()                  { }
         public void TriggerPreset(string presetId)  { }
         public void PlaySFXById(string sfxId)       { }
+        public void PlayFormSwitch(int formIndex)   { }
     }
 }