TaCZFirearmClientOptimization

通用功能
- 允许后退时疾跑，且可以不断开疾跑，丝滑从前进过渡到后退以应对高压情况。

沉浸式飞机兼容:
- 飞机视角修复，飞机上第一视角射击方向和实际一致。
- 乘坐飞机时，按 `L` 默认键位，开关飞机虚化，驾驶员和乘客均生效，避免视野遮挡，虚化程度可配置。

General features:
- Allows sprinting backward without interrupting sprint when smoothly switching between forward and backward movement.

Immersive Aircraft compatibility:
- Fixes the aircraft view so the first-person firing direction matches the actual direction.
- Press the default `L` key while riding an aircraft to toggle aircraft fading. It works for both pilots and passengers, reduces view obstruction, and has configurable opacity.