Rename customs-tablet-frontend to public-frontend and add new features

- Rename customs-tablet-frontend/ to public-frontend/ for broader scope
- Add new pages: customs, inspection with camera integration
- Add new services: apiClient.ts, backendApi.ts, normalizers.ts
- Add CameraFrame component for real-time video streaming
- Add scan_fixer module with clock_publisher and timestamp fix utilities
- Update startup scripts to support new frontend structure
- Update arm_server configuration and service files

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

public-frontend/README.md

@@ -0,0 +1,9 @@
+# 海关智慧查验平台前端
+
+这是从 `prototype/` 复刻并重构后的真实后端接入版本。原型目录保持只读，新代码集中在当前目录。
+
+默认通过 Next.js rewrites 将 `/api/*` 与 `/photos/*` 转发到 Flask 后端 `http://127.0.0.1:5000`。如需改后端地址，可设置：
+
+```bash
+BACKEND_URL=http://后端地址:5000 npm run dev
+```