refactor: 替换PresetAIs为PresetBulletAI，优化子弹AI逻辑

scripts/Contents/Characters/Chick.gd

@@ -17,7 +17,7 @@ func spawn():
 	texture.play("walk")
 
 func ai():
-	move(currentFocusedBoss.position - position)
+	PresetEntityAI.follow(self, currentFocusedBoss, 0)
 	if currentFocusedBoss.position.distance_to(position) < 200:
 		tryAttack(2)
 	elif currentFocusedBoss.position.distance_to(position) < 700:

scripts/Contents/Characters/Hen.gd

@@ -8,7 +8,7 @@ func register():
 
 func ai():
 	attackCooldownMap[0] = randi_range(1500, 4000)
-	move(currentFocusedBoss.position - position)
+	PresetEntityAI.follow(self, currentFocusedBoss, 300)
 	tryAttack(0)
 func attack(type):
 	if type == 0: