feat: add request logging via Postgres

[arthurhenrique]

Summary

• add Postgres service to docker compose and environment
• log requests and responses to database using SQLAlchemy
• create startup event to initialize table
• cover request logging with unit test
• add AGENTS instructions to require running tests
• use context manager and exception logging for request logging

Testing

• pytest {{cookiecutter.project_slug}}/tests

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https://chatgpt.com/codex/tasks/task_e_68ac7960ffb88323b93d80f0d0aebfb3

close #43