Axiom-engine pilot model version for Nigeria (rulespec-ng)

Companion to the Ghana pilot issue, same Belgium-pilot pattern (#447/#448): AxiomNigeriaPilot wrapping the rulespec-ng encodings (Nigeria Tax Act 2025 Fourth Schedule rate schedule + s.30 chargeable income and rent relief — merged; validated against the gazette print, GRA-style external anchors and the PwC Worldwide Tax Summaries sample computation; no household oracle exists for Nigeria, which is documented in the lane's oracle index).

Prerequisite: the composed gross-to-tax program (rulespec-ng#3 — s.30 into Fourth Schedule via an axiom-programs spec). Nigeria's modules already chain conceptually (chargeable income feeds the schedule), so this is the thinner of the two adapters.

Motivation: runnable examples of the current Nigerian law (first year of assessment 2026) for the TaxDev/IFS conversation; the 2023-era policyengine-ng package models the repealed PITA regime and is superseded by this path.

🤖 Generated with Claude Code

Compare the Ghana pilot issue and Belgium-pilot pattern in #447/#448, then read the AxiomNigeriaPilot and rulespec-ng#3 references. Confirm how the merged Nigeria Tax Act 2025 modules compose through the axiom-programs spec, and check the lane's oracle index and cited validation anchors. Done means a runnable first-year-2026 Nigeria pilot model using the composed gross-to-tax program.