`_plan_for` now scores the baseline + every cumulative prefix once
(`cascade_scores`, best-practice order) and reuses those Scores for both the
role-3 marginal attribution and a per-measure bill cascade: bill each prefix at
one Fuel Rates snapshot and take consecutive Bill deltas as each measure's
marginal delivered-kWh and £ saving. Saving is signed (ventilation is
negative) and telescopes exactly to the Plan headline savings, because the
Plan's baseline/post Bills are now the same cascade endpoints (`bills[0]` /
`bills[-1]`) — which also drops the redundant standalone baseline `calculate`.
`recommendation.kwh_savings` / `energy_cost_savings` are filled from these.
Adds `Bill.total_consumption_kwh` (shared by Plan + the orchestrator). Pinned
end-to-end on the real calculator: Σ per-measure savings == the Plan totals
(ADR-0014 amendment).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Bill / EnergyBreakdown / BillDerivation / sap_fuel were under
domain/property_baseline/ only because Baseline was built first. The Modelling
stage now needs them too, so move them (and their tests) to a neutral
domain/billing/ — Fuel/FuelRates already live in the shared domain/fuel_rates/.
Avoids a modelling -> property_baseline cross-stage import and a package name
that wrongly implies ownership (ADR-0011, ADR-0014 amendment). Pure git mv +
import rewrite across 10 files; 40 billing/baseline/repo tests pass, pyright
strict clean. CONTEXT.md Bill Derivation location updated.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
