Docker for local development

[Automaticare]

Description
Containerize API + Postgres with docker compose for quick setup.

Acceptance Criteria

• docker compose up starts API + Postgres; app reachable; Alembic auto-migrates.

• Healthchecks for both services.

Technical Notes

• Mount code for live reload in development; environment via .env.

Test Notes

• Fresh machine smoke test.

Subtasks

• Dockerfile

• docker-compose.yml

• Healthchecks + Makefile