Improve Docker startup robustness

[pasmud]

Summary

• Normalize the Docker entrypoint script during image build so Windows CRLF checkouts do not break Linux container startup.
• Default Gunicorn threads to 1 instead of 0 to avoid hung HTTP requests.
• Remove an unused Compose network that only attached to the app service.

Validation

• docker compose config
• docker compose build app
• docker compose run --rm --no-deps app bash -n run.sh