Initial commit: 3D Viewer application

Features:
- Vue 3 frontend with Three.js/Online3DViewer
- Node.js API with PostgreSQL and Redis
- Python worker for model conversion
- Docker Compose for deployment
- ViewCube navigation with drag rotation and 90° snap
- Cross-section, exploded view, and render settings
- Parts tree with visibility controls

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

risks.csv

@@ -0,0 +1,5 @@
+风险ID,风险描述,发生概率,影响程度,风险等级,缓解措施,负责人,状态
+R1,STEP 转换失败率高,中,高,高,多引擎回退 (cascadio → OpenCASCADE),后端,监控中
+R2,大文件上传超时,中,中,中,分片上传 + 断点续传,全栈,待处理
+R3,3D渲染性能问题,低,中,低,WebGL降级 + LOD,前端,待处理
+R4,依赖包安全漏洞,低,高,中,定期 npm audit / pip check,DevOps,监控中