Add Medicaid long-term care home equity limit

[daphnehanse11]

Closes #5984.

Summary

• Add the 2028 Medicaid long-term care home-equity cap from H.R. 1 Sec. 71108.
• Apply the cap to Medicaid eligibility for long-term care recipients, with the agricultural-lot exception.
• Add home-equity inputs and targeted Medicaid eligibility tests.

Tests

• uv run python -m policyengine_core.scripts.policyengine_command test policyengine_us/tests/policy/baseline/gov/hhs/medicaid/eligibility/is_medicaid_long_term_care_home_equity_eligible.yaml policyengine_us/tests/policy/baseline/gov/hhs/medicaid/eligibility/is_medicaid_eligible.yaml -c policyengine_us
• uv run pytest policyengine_us/tests/test_parameter_files.py policyengine_us/tests/test_system_import.py -q

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (8f458cd) to head (e3f2449).
⚠️ Report is 28 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main     #8341   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            4         6    +2     
  Lines           52        74   +22     
  Branches         0         1    +1     
=========================================
+ Hits            52        74   +22     

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

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