Rename workspace_dir to shared_dir and add sales analyst example

[andybbruno]

Summary

• Renames workspace_dir to shared_dir and documents the host↔container bind mount at /shared (shell cwd inside the container).
• Simplifies sandbox identity: uses a short UUID for sandbox.id instead of docker inspect, and removes unused inspect_container_id helper.
• Relaxes default container hardening (drops read-only rootfs / cap-drop from the default docker run profile) while keeping memory/CPU/PID limits.
• Adds examples/sales_analyst.py with sample examples/data/sales.csv, and updates the pizza agent + README accordingly.

Breaking changes

• Constructor parameter workspace_dir → shared_dir
• Container mount path /workspace → /shared

Test plan

• pytest tests/ passes locally
• DockerSandbox(shared_dir="examples/data") starts a container and mounts the host folder at /shared
• Run examples/pizza_agent.py (network required) and confirm recipe.md appears under examples/data/
• Run examples/sales_analyst.py and confirm sales_report.md + img/ are produced in the shared folder

Made with Cursor