Block ACA eligibility after Medicaid work requirement failure

[daphnehanse11]

Fixes #6174.

Summary

• Adds a Medicaid-side indicator for people otherwise Medicaid-eligible but denied by work requirements.
• Treats that work-requirement denial as ACA marketplace premium/PTC blocking coverage.
• Adds ACA premium/PTC regressions for Medicaid work-requirement failure and a non-Medicaid control case.

Tests

• uv run python -m policyengine_core.scripts.policyengine_command test policyengine_us/tests/policy/baseline/gov/aca/eligibility/pays_aca_premium.yaml -c policyengine_us
• git diff --check

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (47cb26b) to head (ef40f86).
⚠️ Report is 13 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main     #8722   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            3         2    -1     
  Lines           47        39    -8     
  Branches         0         2    +2     
=========================================
- Hits            47        39    -8     

Flag	Coverage Δ
unittests	100.00% <100.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.