Prioritize CTC fiscal target calibration

[MaxGhenis]

Summary

• boost direct CTC total calibration loss weight using structured target_role metadata
• require direct CTC total in the US fiscal target coverage gate
• add CTC amount to builder and release-contract critical fit gates at 20% max relative error

Validation

• uvx ruff check tools/build_us_fiscal_refresh_release.py packages/populace-build/src/populace/build/us/fiscal_targets.py packages/populace-build/tests/test_us_fiscal_refresh_builder.py packages/populace-build/tests/test_us_fiscal_targets.py packages/populace-data/src/populace/data/contract.py packages/populace-data/tests/test_contract.py
• .venv/bin/python -m pytest packages/populace-build/tests/test_us_fiscal_refresh_builder.py packages/populace-build/tests/test_us_fiscal_targets.py packages/populace-data/tests/test_contract.py -q

Notes

• Real 2024 Ledger target registry check: ctc_total weight 19.2116, EITC weight 1.3726, ACTC weight 0.7850.
• A 64-epoch local smoke was stopped before solve because target-frame materialization pushed swap to 10.3/11.3 GB; no release artifact was produced.