feat(战斗系统): 添加新武器"树"及其配套子弹和特效

实现新的近战武器"树"，包含以下内容：
- 添加武器Tree.gd脚本及场景资源
- 新增Parrier子弹类型，支持子弹碰撞检测和反弹效果
- 添加武器攻击音效和子弹命中特效
- 修改BulletBase.gd以支持子弹间碰撞逻辑
- 更新角色预设装备新武器

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