Add GET /api/v1/attachments/{id} endpoint for downloading attachments
through the MCP proxy. This complements the existing upload endpoint and
enables complete attachment workflows via the proxy API.
- Add scripts/test-runner.py with rich progress bars and fail-fast behavior
- Add rich>=13.0.0 as dev dependency
- Update Makefile: `make test` now runs all tests (unit + integration)
- Test runner shows live progress, current test, and summary
Now `make test` runs both unit and integration tests with docker
containers, matching the docker-service-architecture skill guidelines.
