Treat PE-US aggregate outputs as formula-owned

[MaxGhenis]

Summary

• treat PE-US adds/subtracts variables as formula-owned outputs in the adapter, matching direct formulas
• keep dividend exports leaf-only: derive/export qualified_dividend_income and the non-qualified residual leaf, and block dividend_income / ordinary_dividend_income
• keep SOI ordinary-dividend targets PE-aligned as ordinary_dividend_income, while preserving source_variable=ordinary_dividends for source/provenance semantics
• keep Social Security exports leaf-only by routing generic PUF/legacy totals into social_security_retirement source support and blocking the aggregate social_security
• keep partnership/S-corp exports leaf-only: PE-US computes the aggregate from partnership_income and s_corp_income; Populace no longer synthesizes a tax-unit partnership/S-corp aggregate in PUF support
• replace release-export formula-column cleanup with a hard assertion: formula-owned columns now fail before export instead of being seeded, repaired, dropped, or stripped

TDD notes

• added writer tests proving dividend_income, social_security, partnership_s_corp_income, and generic adds outputs such as employment_income block export
• added release-builder tests proving formula-owned columns raise before calibrated export, while leaf-only frames still receive calibrated weights
• added target metadata coverage for the source-vs-PE variable split on ordinary dividends
• audited cached/current artifacts: dividend and Social Security aggregates were co-exported with leaves and inconsistent; partnership/S-corp cached artifacts did not co-export the aggregate with leaves, but this PR still blocks that future failure mode

Tests

• uv run ruff check packages/populace-build/src/populace/build/us_runtime/fiscal_targets.py packages/populace-build/tests/test_us_fiscal_targets.py tools/build_us_fiscal_refresh_release.py
• uv run pytest packages/populace-build/tests/test_us_fiscal_targets.py — 63 passed
• uv run pytest packages/populace-frame/tests/test_policyengine_us_adapter.py packages/populace-build/tests/test_us_puf_support.py packages/populace-build/tests/test_us_fiscal_refresh_builder.py::test_export_frame_rejects_formula_owned_columns packages/populace-build/tests/test_us_fiscal_refresh_builder.py::test_export_frame_accepts_leaf_only_columns — 36 passed, 1 PE-US warning
• uv run pytest packages/populace-frame/tests/test_policyengine_us_adapter.py packages/populace-build/tests/test_us_puf_aggregate_records.py packages/populace-build/tests/test_us_source_runtime.py packages/populace-build/tests/test_us_plan.py packages/populace-build/tests/test_us_puf_support.py packages/populace-build/tests/test_us_fiscal_targets.py packages/populace-build/tests/test_us_fiscal_refresh_builder.py::test_export_frame_rejects_formula_owned_columns packages/populace-build/tests/test_us_fiscal_refresh_builder.py::test_export_frame_accepts_leaf_only_columns packages/populace-build/tests/test_us_fiscal_refresh_builder.py::test_soi_component_amounts_use_source_specific_signs packages/populace-build/tests/test_us_fiscal_refresh_builder.py::test_soi_indicator_rows_flag_positive_component_items — 158 passed, 1 PE-US warning

[MaxGhenis]

This PR is green but should be merged/released after PolicyEngine/policyengine-us#8747 lands and a compatible policyengine-us release is available. The current Populace lock resolves policyengine-us==1.729.0, which does not expose ordinary_dividend_income or cbo_net_business_income; those are added in #8747 and are needed for the source-aligned target mappings here. The export-surface fix itself is assertion-only: formula-owned columns fail before export rather than being repaired or dropped.