Create: Sentry Mechanical Arm_非官方移植

修复了哨戒臂的子弹位置不对齐、远距离命中率低、双重枪线、实体子弹武器偏移、渲染空指针崩溃、Contraption 枪口/抛壳缺失等问题。通过反编译 TACZ EntityKineticBullet 确定了子弹位置的精确计算公式，改用向量计算替代固定偏移，并添加 hasEntityBullet() 智能检测机制。/

Fixed sentry arm bullet misalignment, poor long-range accuracy, double gun lines, entity bullet weapon offsets, rendering NPE crashes, and missing contraption muzzle/shell ejection. By decompiling TACZ's EntityKineticBullet, determined the exact bullet position formula and replaced fixed offsets with angle-aware vector calculations, with an intelligent hasEntityBullet() detection system added.