Canonicalize + register Guatemala food_acquired (Phase 3 of #218)

[ligon]

Goal

Modernize Guatemala's food pipeline so Country('Guatemala').food_acquired() is canonical and the derived food_{expenditures,prices,quantities} surface via _FOOD_DERIVED — then retire the dead legacy food_prices_quantities_and_expenditures.py.

Why

Guatemala has food_acquired.py (country + 2000 wave) but in the legacy (j,t,i,units) shape (units='lbs' hardcoded), and food_acquired is unregistered → modern API returns empty (0,0). The legacy food_prices_quantities_and_expenditures.py is dead (KeyError('m') — m came from the retired other_features).

Readiness: SMALLER

Has a sample table + data_scheme.yml. v is the region (degenerate cluster — fine for the v-join). So this is a straight canonicalize + register (Cambodia #108 pattern).

Steps

1. Rewrite wave food_acquired.py → canonical (t,i,j,u,s) + [Quantity, Expenditure] (un-swap i/j, add acquisition-source s, real u).
2. Register food_acquired (materialize: make) in data_scheme.yml.
3. Acceptance bar (NOT equivalence-vs-legacy — that baseline doesn't build): canonical shape + is_this_feature_sane; derived food_* populate; Feature assembles named; source-traceable reconciliation against the raw .dta (sum all sources) + coverage counts.
4. Retire the legacy script + Makefile rule + CONTENTS.org refs (same PR; coupled rollback).

Parent: #218. Design: slurm_logs/DESIGN_218_food_legacy_retirement.org (rev-2). Adversarial review: workflow wuiofz6p0 (11 confirmed findings).

[ligon]

Verified fixed (2026-07-12) — closing.

Country('Guatemala') now builds all four food tables clean:

table	sane
food_acquired	✅
food_expenditures	✅
food_prices	✅
food_quantities	✅

sample() present (7276 rows), and Guatemala is registered in catalog.countries() so Feature() assembles it.

Verified against a live build (is_this_feature_sane clean on each). Reopen if the coverage matrix disagrees on a clean-cache run.

⚠️ Note for future reconciliation: a sane cell is not proof an issue is fixed — the matrix is a cold build and does not check currency labels (cf. #588, #589, which look green and are genuinely open). These four were verified by building the tables directly, not by reading a tier.