Add CalcsLive custom node workflow - engineering calculations demo

- Showcases @calcslive/n8n-nodes-calcslive custom node capabilities
- Demonstrates cylinder geometry and mass calculations
- Includes calculation chaining and email reporting
- Template for engineering automation workflows
- Add .e3d/ to .gitignore for development isolation

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

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