feat: Implement Room Streaming System

- Add RoomStreamingManager to manage room loading and unloading based on player proximity.
- Create StreamingBudgetConfigSO for memory and performance budgeting of the streaming system.
- Introduce TransitionDirector to handle seamless and atmospheric fade transitions between rooms.
- Develop WorldGraph to represent room connectivity and facilitate neighbor queries and distance calculations.
- Implement RoomNode and RoomEdge classes to structure room data and connections.

Assets/_Game/Scripts/Enemies/Abilities/CeilingDropAbility.cs

@@ -0,0 +1,91 @@
+using System.Collections;
+using UnityEngine;
+using BaseGames.Combat;
+
+namespace BaseGames.Enemies.Abilities
+{
+    /// <summary>
+    /// 挂顶下落能力：怪物初始挂在天花板（kinematic，重力 0）。能力触发后：
+    /// 1. 切换为 dynamic + 恢复重力
+    /// 2. 自由落体到接触地面
+    /// 3. 落地播放 AoE HitBox + 砸地反馈
+    /// </summary>
+    [RequireComponent(typeof(Rigidbody2D))]
+    public sealed class CeilingDropAbility : EnemyAbilityBase
+    {
+        [Header("下落")]
+        [SerializeField] private float _fallGravityScale = 3.5f;
+        [SerializeField] private float _maxFallTime      = 3f;
+        [SerializeField] private LayerMask _groundMask;
+
+        [Header("落地")]
+        [SerializeField] private HitBox _landingHitBox;
+        [SerializeField] private float  _hitBoxActiveTime = 0.2f;
+        [SerializeField] private float  _recoveryTime     = 0.4f;
+
+        private Rigidbody2D _rb;
+        private RigidbodyType2D _origBodyType;
+        private float           _origGravityScale;
+
+        protected override void Awake()
+        {
+            base.Awake();
+            _rb = GetComponentInParent<Rigidbody2D>();
+        }
+
+        protected override IEnumerator ExecuteCoroutine()
+        {
+            if (_rb == null) yield break;
+            var atk = (_config.attackSequence != null && _config.attackSequence.Length > 0)
+                ? _config.attackSequence[0] : null;
+
+            Phase = AbilityRunState.Active;
+
+            // 切换到动态 + 恢复重力
+            _origBodyType    = _rb.bodyType;
+            _origGravityScale = _rb.gravityScale;
+            _rb.bodyType    = RigidbodyType2D.Dynamic;
+            _rb.gravityScale = _fallGravityScale;
+            _rb.velocity    = Vector2.zero;
+
+            float t = 0f;
+            while (t < _maxFallTime)
+            {
+                t += Time.fixedDeltaTime;
+                yield return new WaitForFixedUpdate();
+                if (t > 0.05f && IsGrounded()) break;
+            }
+
+            _rb.velocity = Vector2.zero;
+
+            if (_landingHitBox != null)
+            {
+                _landingHitBox.Activate(atk != null ? atk.damageSource : null, _transform);
+                yield return EnemyAbilityWaits.Get(_hitBoxActiveTime);
+                _landingHitBox.Deactivate();
+            }
+
+            yield return EnemyAbilityWaits.Get(_recoveryTime);
+
+            // 落地后不恢复挂顶状态（一般转为地面行为），保持动态 Rigidbody
+        }
+
+        private bool IsGrounded()
+        {
+            var hit = Physics2D.Raycast(_rb.position, Vector2.down, 0.6f, _groundMask);
+            return hit.collider != null;
+        }
+
+        protected override void OnInterrupted(InterruptReason reason)
+        {
+            if (_landingHitBox != null && _landingHitBox.IsActive) _landingHitBox.Deactivate();
+            // 中断时恢复 Rigidbody 原始状态，防止物理参数泄漏
+            if (_rb != null)
+            {
+                _rb.velocity     = Vector2.zero;
+                _rb.bodyType     = _origBodyType;
+                _rb.gravityScale = _origGravityScale;
+            }
+        }
+    }
+}