Precision truck demo

注意：本项目中模型文件未经过功能性和安全性验证，使用3D打印无法满足使用强度，仅用于外观等非功能性验证。
精准桥示例设计，仅包含底座及轴承、PU和轴承等零件（未包括挂杆和轮轴部分）。特点以下：

1. 45度。
2. 使用了nkia5901组合轴承作为核心旋转机制。
3. 水平横置PU+石墨黄铜直线轴承/衬套作为回弹机制。
4. 公制。
   Note: The model files in this project have not been verified for functionality or safety. 3D printing cannot meet the structural strength requirements; this design is strictly for non-functional aesthetic verification (e.g., appearance testing).
   This is a design example for a precision truck, containing only the baseplate, along with bushings and bearings (the hanger and axles are not included). Key features include:
5. 45-degree baseplate angle.
6. Uses NKIA5901 bearing as the core rotation mechanism.
7. Horizontal bushings combined with graphite-bronze linear bearings/bushings for the rebound mechanism.
8. Metric standard.