feat(子弹): 添加链枪子弹资源与逻辑

添加链枪子弹的图片资源、脚本和场景文件
为RainbowCat子弹添加穿透属性和生命周期
在子弹AI预设中添加面向鼠标的功能

scripts/Contents/AIPresets/Bullet.gd

@@ -10,3 +10,5 @@ static func trace(bullet: BulletBase, target: Vector2, speed: float):
 		bullet.position.angle_to_point(target),
 		speed
 	)
+static func faceToMouse(bullet: BulletBase):
+	bullet.rotation = bullet.position.angle_to_point(bullet.get_global_mouse_position())

scripts/Contents/Bullets/ChainGun.gd

@@ -0,0 +1,6 @@
+extends BulletBase
+
+func ai():
+	PresetBulletAI.faceToMouse(self)
+func applyDot():
+	pass

scripts/Contents/Bullets/RainbowCat.gd

@@ -1,5 +1,7 @@
 extends BulletBase
 class_name RainbowCat
 
+func register():
+	penerate = 1
 func ai():
 	PresetBulletAI.forward(self, rotation)