Preserve household weight fuel uprating

[MaxGhenis]

Summary

• restore the pre-fuel-change household_weight uprating row; the row currently on main came from the failed fuel release build and inflated population calibration
• compute petrol/diesel proxy indices against the household-weight row actually used by the dataset build
• add a storage regression test pinning the restored household-weight row

Tests

• uv run ruff format policyengine_uk_data/tests/test_road_fuel_volume_uprating.py
• uv run ruff check policyengine_uk_data/utils/uprating.py policyengine_uk_data/tests/test_road_fuel_volume_uprating.py
• uv run --frozen pytest policyengine_uk_data/tests/test_road_fuel_volume_uprating.py policyengine_uk_data/tests/test_population_fidelity.py policyengine_uk_data/tests/test_child_limit.py -q