v0.2.1 - Prometheus Metrics

What's Changed

• Added GET /api/v1/metrics/prometheus for Prometheus-style scraper integrations.
• Fixed app metadata so FastAPI reports the package version consistently.
• Made latest alert delivery ordering deterministic when records share a timestamp.

Validation

• python -m ruff check .
• python -m mypy app
• python -m pytest with 38 passing tests