Capture 60-64 ABAWD-subject SNAP recipients in Medicaid CE pass-through

[DTrim99]

Closes #8969.

The Medicaid community engagement (CE) SNAP pass-through under 42 CFR 435.554(c)(7) is a status test: a SNAP recipient who is subject to a SNAP work requirement is excluded from the CE requirement. It previously tested subject-to status using only the general SNAP work requirement, whose age exemption begins at 60 — so post-HR1 adults aged 60–64, who are exempt from the general requirement but subject to the ABAWD time limit (HR1/P.L. 119-21 raised the ABAWD age range to 64), were not captured.

Change

• is_snap_abawd_exempt (new) — the ABAWD exemption set (age, disability, pregnancy, work-registration exemptions, Indian status, discretionary/area waivers, and the pre-HR1 and good-faith-window variations), extracted from meets_snap_abawd_work_requirements. That variable now returns is_working | is_snap_abawd_exempt — behavior-preserving (its 59-case suite is unchanged).
• is_subject_to_snap_abawd (new) — the ABAWD status test: an able-bodied adult without dependents (no household member under the dependent-age threshold, 7 CFR 273.24(c)(4)) who is not exempt. The household-child gate mirrors meets_snap_work_requirements_person so parents routed around ABAWD aren't over-captured.
• CE pass-through now excludes people subject to the general or ABAWD requirement.

Behavior

Only new-captured population: post-HR1 60–64-year-old ABAWD-subject SNAP recipients (now excluded from CE). Verified no regression for parents of young children or the general age boundary. New/updated tests cover the 60/64/65 boundaries, the pre- vs post-HR1 distinction, and the parent-gate.

Suites: meets_snap_abawd_work_requirements 59/59 (unchanged), CE pass-through + is_subject_to_snap_abawd 65/65.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (8326a14) to head (63040a4).
⚠️ Report is 53 commits behind head on main.

Additional details and impacted files

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  Files           12         4    -8     
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- Hits           161        88   -73     

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unittests	100.00% <100.00%> (ø)

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