Phase 1: persistent FHIR store (Postgres)

[Ciprian-LocalPulse]

• Add PostgresFHIRStore behind the existing FHIRStore interface
• Add Alembic migrations
• Add docker-compose.postgres.yml opt-in override
• Fix blocking store calls in async routes (run_in_threadpool)
• Fix deprecated @app.on_event -> lifespan
• Add integration tests run against a real Postgres in CI

Summary

Describe the behavior and why it is needed.

Verification

• ruff check .
• pytest
• mypy src/medintelos
• npm test when contracts changed

Risk Review

• No real patient data, credentials, private keys, or restricted terminology
• Security and privacy impact considered
• Clinical assumptions and primary sources documented when applicable
• Backward compatibility or migration impact described