feat(战斗系统): 添加招架球子弹和循环计时器功能

实现新的招架球子弹类型(ParryBallBullet)及其相关行为
新增CycleTimer类用于管理子弹的周期性运动
在EntityBase中添加计时器管理功能，支持创建和应用周期计时器
添加招架球子弹的资源文件和相关配置

scripts/Statemachine/CycleTimer.gd

@@ -0,0 +1,23 @@
+class_name CycleTimer
+
+@export var period: float = 1
+
+var startTime: float = 0
+var running: bool = false
+var distance: float = 200
+var bullets: Array[BulletBase] = []
+
+func start():
+	startTime = Time.get_ticks_msec()
+	running = true
+func lifetime():
+	return Time.get_ticks_msec() - startTime
+func periodPercent(count: int):
+	return lifetime() / period * deg_to_rad(360) - deg_to_rad(360.0 * count / len(bullets))
+func apply():
+	bullets = bullets.filter(is_instance_valid)
+	for index in len(bullets):
+		var bullet = bullets[index]
+		bullet.position = bullet.launcher.position + Vector2.from_angle(periodPercent(index)) * distance
+func host(bullet: BulletBase):
+	bullets.append(bullet)