Metric Catalog

Every metric is defined once in the governed catalog (metrics_catalog.yml), implemented once in fct_metric_values, and locked by a dbt test that asserts the computed value equals the catalog's golden value. Change a definition and the value + this catalog move in the same commit — that diff is the audit trail.

The expected_window_value is the canonical result over 2025-09 → 2026-03 on the deterministic dataset (seed=42). tests/assert_metric_values_match_catalog.sql fails the build if the implementation ever disagrees with this contract.