Thread the per-factor source through impact_for() instead of discarding it.
Numeric output (energy_wh, co2e_g) is byte-identical — this is a reporting
change, not a recalculation.
#6 persistence: additive columns tokens_measured, tokens_estimated and
factor_revision (a stable hash of the factor table) on metrics_daily, added via
the existing guarded ALTER TABLE idiom in both app/main.py and
metrics_snapshot.py. Existing rows keep NULL.
#4 API: metrics_series() selects the new columns and derives a per-row
provenance indicator (measured | mixed | estimated | none) from the split; both
/admin/metrics/series and /broker/metrics return it. NULL/unknown splits report
'none', never a confident 'measured'.
docs/energy-metrics.md documents the indicator, the new columns, and the
forward-only-vs-backfill behaviour.
