Carry local geography needed for SNAP ABAWD waiver modeling

Parent: #248

Problem

PolicyEngine-US may need local geography, such as county or borough, to model state/local SNAP ABAWD waiver rules. The immediate example is Alaska borough-level ABAWD waivers.

Populace has congressional-district geography in the audited H5, but the release/build paths searched for this audit did not obviously carry county/borough geography through the final PolicyEngine-facing output. If rules depend on local waiver geography and Populace only exports state/CD fields, microsimulation will not be able to distinguish waived from non-waived localities.

Proposed scope

• Inventory current Populace US geography outputs at household level.
• Confirm whether county_fips, county, puma, or another local geography variable is available or can be reconstructed safely.
• Decide which PolicyEngine-US geography input should support SNAP ABAWD waiver rules.
• Carry the selected geography through the final H5 if the source supports it.
• Add validation diagnostics for missingness and state/local consistency.
• Coordinate with PolicyEngine/policyengine-us#8822.

Out of scope

• Implementing the Alaska waiver formula itself in PolicyEngine-US.
• Adding congressional-district SNAP hard targets.

Acceptance criteria

• Populace documents whether it can support local SNAP waiver geography.
• If supported, the selected local geography variable is present in the output with low or documented missingness.
• If unsupported, the limitation is explicit for OBBBA SNAP work-requirement research.
• The output geography aligns with the variable PolicyEngine-US uses for local waiver rules.

Start by inventorying household-level geography in the audited H5 and tracing the release/build paths into the final PolicyEngine-facing output. Compare available fields such as county_fips, county, and puma with the geography expected by PolicyEngine-US issue #8822. Done means the supported or unsupported local geography is documented, and supported output includes missingness and state/local consistency validation.