feat(intents): dcy-011 buy intent portfolio_id 필수 계약 + ledger skip 가시화 (BAT-015)

dcy-011 전 주기 delivery. issue #6(buy 식별자 정정) + issue #11(ledger silent skip) 흡수.
거버넌스: 기존 Implemented REQ는 change-req, 신규 기능만 신규 REQ(OQ-3).

- REQ-007 (change-req): buy admission portfolio_id 필수화 + SnapshotStore symbol
  resolve + unknown_portfolio 거부 (hard cutover, OQ-1/OQ-2)
- REQ-021 (change-req): buy 메시지 payload symbol 제거
- REQ-018 (change-req): _record_ledger skip 가시화 (WARN + ledger_skipped 카운터)
- REQ-055 (신규): closed↔ledger_outbox anti-join 운영 점검 find_ledger_gap_slots

코드: intents.py(BuyIntent portfolio_id 필수 + resolve_symbol 주입 + _admit_buy
reject 분기), messaging_handlers.py, runtime/daemon.py(_resolve_symbol 배선),
execution.py(skip WARN 로그), adapters/persistence/ops_checks.py(신규 anti-join).

검증: 단위 282 passed/32 skipped, 인프라 게이트(PG+RabbitMQ) 314 passed, ruff clean.
BAT-015(standard) release-candidate. srs/index Next ID → REQ-056.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/application/test_messaging_snapshot_consumer.py

@@ -36,7 +36,7 @@ def test_snapshot_returns_all_slots_and_capacity():
     repo, svc, intents = _wire()
     intents.submit_buy(BuyIntent(
         intent_id="b1", trading_date=DAY, symbol="005930", qty=10,
-        strategy_id="A",
+        strategy_id="A", portfolio_id="PF-1",
     ))
     handler = make_snapshot_rpc_handler(repo, svc)
     resp = handler(_req())
@@ -51,6 +51,7 @@ def test_snapshot_open_view_filters_to_active_slots():
     repo, svc, intents = _wire()
     intents.submit_buy(BuyIntent(
         intent_id="b1", trading_date=DAY, symbol="005930", qty=10, strategy_id="A",
+        portfolio_id="PF-1",
     ))
     handler = make_snapshot_rpc_handler(repo, svc)
     resp = handler(_req(view="open"))
@@ -63,9 +64,11 @@ def test_snapshot_strategy_id_filter():
     repo, svc, intents = _wire()
     intents.submit_buy(BuyIntent(
         intent_id="b1", trading_date=DAY, symbol="005930", qty=10, strategy_id="A",
+        portfolio_id="PF-1",
     ))
     intents.submit_buy(BuyIntent(
         intent_id="b2", trading_date=DAY, symbol="000660", qty=5, strategy_id="B",
+        portfolio_id="PF-2",
     ))
     handler = make_snapshot_rpc_handler(repo, svc)
     resp = handler(_req(view="open", strategy_id="A"))