feat: wire field_contract into product enrichment; auto-discover CRT/CONTRIBUINTE_IPI at heartbeat; targeted per-product ERP evidence

field_contract.resolve_product was only exercised by its own unit tests. /v1/products/resolve now calls it for every product whose NCM
resolves, merging CFOP/CST/CSOSN/PIS-COFINS/CST_IPI/SITUACAO_TRIBUTARIA/IAT/IPPT decisions alongside CLASSIFICACAO_FISCAL/CEST/IPI - reusing
the same engine, the same FiscalContextEntry table the blocker-resolution workflow already writes to, no duplicated rules.

Closes three real transport/discovery gaps found while wiring it in:
- Agent heartbeat never sent company_crt (env-var UF only) or company_contribuinte_ipi, so Installation.company_crt stayed permanently empty
  even though company_context.resolve() already proves both from C000004/EMISSOR for every coverage job. Resolved once, cached, retried only
  while unresolved. Migration 0032 adds Installation.company_contribuinte_ipi (NULL=unknown, never coerced to "N").
- The Agent's enrichment payload only ever reported 3 old fields (CLASSIFICACAO_FISCAL/CEST/IPI) as "current", so the Hub could never see the
  product's own CFOP/CST/CSOSN/... nor the classification columns (TIPO/PROD_COZINHA/PRODUTO_SERVICO/CODGRUPO) infer_role needs - separated
  into a read-only CURRENT_REPORT_FIELDS list, the write allowlist (PRODUCT_ENRICHMENT_WRITE_V1) untouched.
- Added a targeted, product_code-scoped evidence query (firebird_reader.read_product_evidence: recipes/composed/purchases/stock, indexed WHERE,
  never a full-table scan) so st_withheld/product_role can be proven for a single ad-hoc resolve, not only during a full sync job.

Verified read-only against the real database (D:\PROJETOS\GTISISTEMAS\Banco\GTI.FDB): CRT=1, CONTRIBUINTE_IPI=N, company_context.resolve()
reaches HIGH confidence; infer_role correctly resolved RESALE/OWN_PRODUCTION for 5/8 sample real products with zero operator questions.

1121 tests passed (tests + central/tests + agent/tests), 0 failed. Version 1.3.7 (single GTI_FISCAL_VERSION shared by Hub and Agent per
central/app/version.py's own design - never independently versioned).

tests/test_release_candidate.py

@@ -14,11 +14,11 @@ sys.path.insert(0, str(ROOT))
 def test_versions_are_coherent_across_hub_agent_and_packages():
     from central.app.version import GTI_FISCAL_VERSION
     v = (ROOT / "release" / "VERSION").read_text(encoding="utf-8").strip()
-    assert v == GTI_FISCAL_VERSION == "1.3.6"
+    assert v == GTI_FISCAL_VERSION == "1.3.7"
     pep = v.replace("-rc", "rc")
     for pp in ("central/pyproject.toml", "agent/pyproject.toml"):
         assert f'version = "{pep}"' in (ROOT / pp).read_text(encoding="utf-8")
-    assert '"AGENT_VERSION", "1.3.6"' in (ROOT / "agent" / "scripts" / "run_agent_service.py").read_text(encoding="utf-8")
+    assert '"AGENT_VERSION", "1.3.7"' in (ROOT / "agent" / "scripts" / "run_agent_service.py").read_text(encoding="utf-8")
     manifest = ROOT / "release" / "RELEASE_MANIFEST.json"
     if manifest.exists():
         m = json.loads(manifest.read_text(encoding="utf-8"))