Fix business income SECA and LSR inputs

[MaxGhenis]

Summary

• Copy direct self-employment and SSTB self-employment inputs into their before-LSR holders in household and microsimulation runs.
• Use Schedule F farm operations income, not Schedule J farm income, for taxable self-employment income, market income, and state/program income source lists.
• Add regression tests for the LSR wiring, farm SECA source behavior, farm operations market income, and affected MA/NJ/CT farm-income cases.
• Avoid eager divide-by-zero warnings in self-employment response and QBI/SSTB QBI allocation shares.

Companion data PR: PolicyEngine/policyengine-us-data#828

Root cause

The household Simulation constructor iterated over the emptied employment-income holder when moving self-employment inputs into before-LSR storage. SSTB self-employment had before-LSR plumbing but no constructor transfer. SECA and multiple downstream income source lists also referenced the Schedule J-style farm_income input where they meant Schedule F farm_operations_income.

Tests

• ruff check on touched Python files
• .venv/bin/python -m pytest policyengine_us/tests/core/test_business_income_regressions.py policyengine_us/tests/test_parameter_files.py -q
• .venv/bin/python -m pytest policyengine_us/tests/core/test_business_income_regressions.py policyengine_us/tests/core/test_behavioral_response_measurements.py -q
• .venv/bin/python -m policyengine_core.scripts.policyengine_command test policyengine_us/tests/policy/baseline/gov/irs/self_employment/taxable_self_employment_income.yaml policyengine_us/tests/policy/baseline/gov/irs/income/taxable_income/deductions/qbid/qualified_business_income.yaml policyengine_us/tests/policy/baseline/gov/irs/income/taxable_income/deductions/qbid/sstb_qualified_business_income.yaml policyengine_us/tests/policy/baseline/gov/irs/income/taxable_income/deductions/qbid/qualified_business_income_deduction.yaml -c policyengine_us
• .venv/bin/python -m policyengine_core.scripts.policyengine_command test policyengine_us/tests/policy/baseline/household/income/person/market_income.yaml policyengine_us/tests/policy/baseline/household/income/household/household_market_income.yaml -c policyengine_us
• .venv/bin/python -m policyengine_core.scripts.policyengine_command test policyengine_us/tests/policy/baseline/gov/states/ma/tax/income/gross_income/integration.yaml policyengine_us/tests/policy/baseline/gov/states/nj/tax/income/taxable_income/nj_gross_income.yaml policyengine_us/tests/policy/baseline/gov/states/ct/oec/c4k/ct_c4k_countable_income.yaml policyengine_us/tests/policy/baseline/household/income/person/market_income.yaml policyengine_us/tests/policy/baseline/household/income/household/household_market_income.yaml -c policyengine_us
• .venv/bin/python -m policyengine_core.scripts.policyengine_command test policyengine_us/tests/policy/baseline/gov/states/ct/oec/c4k/ct_c4k_family_fee.yaml policyengine_us/tests/policy/baseline/gov/states/mi/tax/income/mi_household_resources.yaml -c policyengine_us
• uv run python policyengine_us/tests/run_selective_tests.py --base-branch upstream/main --coverage
• .venv/bin/python -m pytest policyengine_us/tests/core -q
• uv run --extra dev towncrier check --compare-with upstream/main --staged

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (20705b0) to head (605353b).
⚠️ Report is 26 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##             main     #8156       +/-   ##
============================================
+ Coverage   85.36%   100.00%   +14.63%     
============================================
  Files           3        10        +7     
  Lines          41       204      +163     
  Branches        2         4        +2     
============================================
+ Hits           35       204      +169     
+ Misses          6         0        -6     

Flag	Coverage Δ
unittests	100.00% <100.00%> (+14.63%)	⬆️

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