Medicaid CE: model recent incarceration exclusion

[daphnehanse11]

Parent issue: #7751

The current Medicaid work requirement implementation can exclude people who are currently incarcerated, but the contributor issue also identifies the recent-incarceration exclusion as a separate gap.

Scope:

• Confirm the exact statutory and CMS guidance wording for the recent-incarceration window.
• Add the smallest stable input needed, probably a boolean such as was_recently_incarcerated_for_medicaid_ce unless a date-based pattern already exists.
• Include current incarceration and recent release in the Medicaid CE exclusion rollup.
• Add tests for current incarceration, recent incarceration, and no incarceration.

Out of scope:

• Application-month lookback logic.
• Operational verification or documentation workflow.

Sources:

• https://www.congress.gov/bill/119th-congress/house-bill/1/text
• https://www.medicaid.gov/federal-policy-guidance/downloads/cib12082025.pdf