Add taxpayer ID primitives to Enhanced CPS

[MaxGhenis]

Summary

• derive taxpayer_id_type, has_valid_ssn, and has_tin from CPS identification status
• keep has_itin as a temporary compatibility alias in the emitted dataset
• add unit coverage and artifact-aware integration checks for the new raw fields

Why

Federal tax rules increasingly distinguish between broader taxpayer-ID requirements and stricter valid-SSN requirements. The CPS pipeline currently only emits ssn_card_type, which forces upstream policy code to infer both concepts indirectly.

This PR adds explicit dataset-level primitives so policyengine-us can consume statute-facing inputs instead of overloading ssn_card_type.

Companion policy PR: PolicyEngine/policyengine-us#7974

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[MaxGhenis]

Superseded by #708: the taxpayer ID primitives and conservative target-based TIN imputation have been folded into the org-branch PR so CI only has one us-data PR to run.