Record cross-family review outcome for handler wiring

GPT-4.1 cross_review.py run against the real handler diff
returned no BLOCK and no security findings; both FIX items
verified as no-change-needed (fallback logging already correct;
non-dict AI output is the pre-existing issue #101 pattern this
PR deliberately does not touch).

Refs: #99

docs/po-template-parser.md

@@ -220,7 +220,7 @@ Plus `missing_required_field` for the required labeled fields (per-item metadata
 - [x] Fallback-rate CloudWatch alarm in `cdk/po_stack.py` — retuned for ~57/day: 6h periods, `IF((fb+tmpl)>=8, …)` volume floor, >20% threshold, eval 4 / datapoints 2 (see the po_stack comment + README for the arithmetic; `npx cdk synth po-ingest` gated).
 - [x] Offline tests + fixtures: goldens for every positive fixture; one adversarial per gate rule (thousands-sep, dup-label swap, Part-Number bullet shift pair, multiline, non-USD, bad status, PO-id/URL mismatch, unlabeled/duplicate bullets, prompt injection); comment + non-Coupa assertions; contract⊆prompt parity test.
 - [x] README updated. Confluence "AWS Architecture Map" update — ⚠️ outstanding (must land with the merge; PO subgraph gains the template-parser stage + fallback alarm).
-- [ ] `cross_review.py` (GPT-4.1) pass — handler contract change (Sea Haven policy). ⚠️ Outstanding until run against the final PR diff — do not merge without it.
+- [x] `cross_review.py` (GPT-4.1) pass — run 2026-07-16 against the real handler diff: **no BLOCK, no security findings, "safe to merge with minor fixes."** Both FIX items verified as no-change-needed: the fallback log line already reports `ai_fallback` correctly (a Claude-side exception propagates before it, unchanged posture), and the non-dict-from-Claude hazard is the pre-existing issue #101 pattern this PR deliberately leaves untouched.
 - [x] `ruff check` + `ruff format` + `pytest` green locally (354 tests; CI must confirm).
 
 **PR #2 — derived-classifier factoring (follow-up)**