[Feature Request] Add OpenAI Agents Memory Examples

[jssmith]

Is your feature request related to a problem? Please describe.

Add samples based on OpenAI Agents SDK memory examples.

Describe the solution you'd like

1. Wrap sqlalchemy_session_example.py. Run it in an activity and add transactional protections to ensure idempotence.
2. Native PostgreSQL implementation similar to advanced_sqlite_session_example.py.
3. OpenAI Conversations implementation similar to openai_session_example.py. We should be able to use conversation_id, which was added recently, to make this more efficient.

Additional context

Preliminary work is on the branch openai/session