- Changed default Docker image version from 'latest' to '17-3.5' in config
- Introduced entity_name var for consistent lookups
- Added POSTGRES_VERSION and POSTGRES_VERSION_MAJOR extraction
- Updated Dockerfile to install postgresql-server-dev-<major> with default fallback to 'all'
- Minor YAML formatting improvements
Ref: https://chatgpt.com/share/68de40b4-2eb8-800f-ab5b-11cc873c3604