Model optional Medicaid community engagement short-term hardship exceptions

## Summary

The June 1, 2026 CMS interim final rule allows states to elect optional short-term hardship exceptions that deem applicable individuals compliant with Medicaid community engagement for affected months. PolicyEngine currently does not model these state-option hardship exceptions.

## Sources

- CMS fact sheet: https://www.cms.gov/newsroom/fact-sheets/medicaid-community-engagement-requirement-certain-individuals-interim-final-rule-comment-period-cms
- IFC text: https://public-inspection.federalregister.gov/2026-11094.pdf
- Current variable: `policyengine_us/variables/gov/hhs/medicaid/eligibility/medicaid_work_requirement_eligible.py`

## Policy Details

Under 42 CFR 435.555, states may provide short-term hardship exceptions for events such as certain institutional or inpatient care, emergencies or disasters affecting ability to demonstrate community engagement, high-unemployment circumstances approved by CMS, and travel outside the community for extended periods by the applicable individual or a dependent. The exception is optional and depends on state plan election and procedures.

## Proposed Modeling Work

Add state-level parameters indicating whether short-term hardship exceptions are elected and which hardship events are active. Add person or household inputs for hardship circumstances where feasible. Decide whether to model hardship exceptions as direct inputs, state parameters, or both.

## Acceptance Criteria

- In a state with the hardship option enabled, an applicable individual with a qualifying hardship event is deemed compliant for the relevant month or annual approximation.
- In a state without the hardship option enabled, the same hardship input does not change eligibility.
- Tests cover enabled and disabled state-option cases.
- Any annual-model approximation of month-specific hardship events is documented.