fix: product_role never infers OWN_PRODUCTION from a single COMPOSICAO occurrence

Missão 4 / Bloco A.1 (prioridade máxima): central.app.field_contract.infer_role
treated ANY C000032.TIPO=COMPOSICAO row for a product as proof of own
production, with no ratio check - a beer sold 19 times and used once as a
recipe component (Agent 2, real data) was classified OWN_PRODUCTION from
that single occurrence, proposing to change its CFOP and IPPT.

New deterministic threshold in field_contract.py: COMPOSICAO must be a
majority (>=70%) of that product's own C000032 movement history, with at
least 5 total events, to count as own-production evidence. Below 30% the
evidence is discarded entirely (falls through to other role evidence,
e.g. TIPO=VENDA -> RESALE). Between 30% and 70% (with enough events to be
meaningful) is genuinely conflicting evidence -> UNKNOWN, never guessed
either way. RECEITA_INGREDIENTES/PROD_COZINHA-based evidence (a direct
recipe-table linkage, not a statistical ratio) is untouched.

agent/src/gti_fiscal_agent/firebird_reader.py now counts COMPOSICAO vs other
C000032 rows per product (read_product_evidence: single indexed query;
read_evidence: one grouped query for the whole catalog) into a new
ev["composed_ratio"] key, alongside the existing "composed" set (kept for
other, non-role consumers like coverage.py). central/app/enrichment/api.py's
sanitize_product_evidence and fiscal_completion.py's empty-ev fallback both
carry the new key through.

New tests (central/tests/test_field_contract.py) cover the 5 real cases named
in the mission: the beer (1 vs 19, 5% - discarded), a second beer (3 vs 4,
42.9% - MIXED/UNKNOWN), the liqueur (34 vs 22, 60.7% - still MIXED/UNKNOWN,
below the 70% bar), the juice with PROD_COZINHA=1+RECEITA_INGREDIENTES
(unaffected, stays OWN_PRODUCTION), and the tilapia/corvina fish (no
composed evidence at all, stays RESALE) - plus a strong 90% majority case
and an insufficient-sample (<5 events) case. A new end-to-end test in
agent/tests/test_cfop_ippt_auto_apply.py (committed separately, see the
feature/cfop-ippt-write branch) proves the weak-evidence beer never reaches
select_candidates as a write candidate, independent of any write flag.

Re-running the dry-run over Agent 2's real database (GTI.FDB, 527 products)
after this fix: AUTO_FILL_SAFE CFOP/IPPT cells drop from 12 to 3 (the two
fish CFOP fills + the juice's IPPT, all with strong, non-statistical
evidence) - docs/runs/GTI_dryrun_universe_summary_after_A1.json. This
corrects the Missão 3 report's 12/9(downgraded)/4(sustained) manual
judgment call with a deterministic, tested engine rule.

No schema/migration change. Zero Firebird writes (read-only analysis only).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

agent/tests/test_enrichment.py

@@ -136,7 +136,7 @@ def test_current_report_includes_fiscal_completion_and_classification_columns(tm
     assert sent["CSOSN"] == "102" and sent["TIPO"] == "VENDA"
     for f in E.FISCAL_COMPLETION_FIELDS + E.CLASSIFICATION_CONTEXT_FIELDS:
         assert f in sent, f
-    assert hub.resolve_calls[0]["ev"] == {"recipes": [], "composed": [], "purchases": {}, "stock_entry": {}, "stock_in": {}}   # targeted evidence rides along (empty here: sqlite has no RDB$RELATION_FIELDS)
+    assert hub.resolve_calls[0]["ev"] == {"recipes": [], "composed": [], "composed_ratio": {}, "purchases": {}, "stock_entry": {}, "stock_in": {}}   # targeted evidence rides along (empty here: sqlite has no RDB$RELATION_FIELDS)
 
 
 def test_existing_value_is_never_overwritten(env):

agent/tests/test_firebird_reader_product_evidence.py

@@ -25,7 +25,7 @@ def test_no_firebird_system_table_degrades_to_no_evidence_never_raises():
     gracefully to "no evidence", exactly like a missing table would, never raise."""
     db = sqlite3.connect(":memory:")
     ev = read_product_evidence(db, "000001")
-    assert ev == {"recipes": set(), "composed": set(), "purchases": {}, "stock_entry": {}, "stock_in": {}}
+    assert ev == {"recipes": set(), "composed": set(), "composed_ratio": {}, "purchases": {}, "stock_entry": {}, "stock_in": {}}
 
 
 def test_targeted_lookup_is_scoped_to_the_one_product_code():
@@ -82,4 +82,4 @@ def test_targeted_lookup_is_scoped_to_the_one_product_code():
     ev = read_product_evidence(conn, "000013")
     assert ev["stock_entry"] == {"000013": True} and ev["stock_in"] == {"000013": True}
     ev = read_product_evidence(conn, "999999")
-    assert ev == {"recipes": set(), "composed": set(), "purchases": {}, "stock_entry": {}, "stock_in": {}}
+    assert ev == {"recipes": set(), "composed": set(), "composed_ratio": {}, "purchases": {}, "stock_entry": {}, "stock_in": {}}