Add the NZ transport contract and real-Axiom Frame bridge

Part of #343. Add a spec-only NZ transport package and a verified Frame-to-Axiom boundary before attempting a population calibration.

Acceptance:

• Pin the public US donor artifact by immutable revision, filename, SHA-256, and byte size; retain donor/support provenance.
• Pin the reviewed NZ RuleSpec input/output contract and cell identities for Chronicle WFF/IWTC administrative counts. Keep official Budget scores and entitlement dollars held out from calibration.
• Add a closed person/household/family export contract: eleven substantive inputs are mandatory, ten unrelated eager inputs may be explicit padding zeros, and only household weights are stored.
• Extend the generic Axiom adapter for canonical RuleSpec roots, explicit tax-year bounds, exact-bounded Decimal input conversion, and exact HDF persistence.
• Exercise actual Axiom native software on a tiny nonuniform household/family fixture, including missing-input, membership, weight, and formula-owned export refusals.
• Document the reusable three-parallel-lane country expansion playbook and the explicit gates before a calibrated release/dashboard publication/official-score replication.

This issue does not authorize a fabricated or uncalibrated NZ release. Donor-to-NZD/family/period bridges, reviewed fact bindings, shared build operators, calibration thresholds, Treasury source activation, and an official operating-cost accounting bridge remain on the parent epic before publication.

Start with the generic Axiom adapter, the RuleSpec input/output contract, and the tiny nonuniform household/family fixture described in the acceptance criteria. Trace the required donor provenance, closed export contract, exact Decimal/HDF handling, native Axiom refusal checks, and country-expansion documentation. Done means all listed contracts and gates are verified without publishing an uncalibrated NZ release.