feat(ledger): dcy-018 option D cash/position write-back + 추정 현금 (BAT-023)

ledger write 응답의 portfolio-hub 권위 cash/quantity 를 스냅샷에 write-back 해
매수/매도 직후 "수량 live·현금 stale" 비대칭 제거(option D 활성화). portfolio-hub#8
(*_after 응답) 동작 중 확인으로 그간 deferred 됐던 REQ-030 을 닫음.

거버넌스: 전부 change-req (신규 REQ 없음, dcy-018 OQ-3 a).
- REQ-017: record_trade → LedgerWriteOutcome{result, cash_balance_after,
  asset_quantity_after}. 어댑터가 응답 root flat *_after 파싱(new+duplicate, 누락 None)
- REQ-019: LedgerWriter 에 SnapshotStore 주입 → new+duplicate write-back
  (best-effort, *_after 절대값이라 멱등). LedgerOutbox.pending_cash_delta()
- REQ-029: 추정 현금 오버레이(_apply_cash_estimate, cash_estimated 라벨, OQ-4 i)
  + 슬롯 오버레이 유지(OQ-1 B). 미정산 outbox delta 기반, write-back 수렴
- REQ-030: option D 활성화 → Approved→Implemented

best-effort 격리(NFR-1): write-back/추정 실패가 ledger 멱등·청산 무차단.
배치 번호: 동시 커밋된 BAT-022(slot-state, dcy-016)와 충돌해 BAT-023 으로 배정.

검증: 단위 350 passed/35 skipped, 인프라 게이트(PG+RabbitMQ) 385 passed, ruff clean.
신규 test_ledger_option_d + adapter/PG 테스트. BAT-023 release-candidate.

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

trex_core/runtime/daemon.py

@@ -147,15 +147,16 @@ class Daemon:
         )
         self.broker = _build_broker(config)
         self.outbox = PostgreSQLLedgerOutbox(config.dsn)
+        # BAT-008: portfolio-hub read + snapshot store + durable pause + scheduler.
+        # (Created before the ledger writer so option-D write-back can target it.)
+        self.snapshot_store = SnapshotStore()
         self.ledger_writer = LedgerWriter(
             self.outbox, _build_ledger(config),
+            snapshot_store=self.snapshot_store,  # dcy-018 / REQ-030: option D write-back
             retry_base_sec=config.ledger_retry_base_sec,
             retry_cap_sec=config.ledger_retry_cap_sec,
             max_attempts=config.ledger_max_attempts,
         )
-
-        # BAT-008: portfolio-hub read + snapshot store + durable pause + scheduler.
-        self.snapshot_store = SnapshotStore()
         # BAT-010/011: per-slot watchdog (snapshot RPC writer, safety-sell reader).
         self.watchdog = WatchdogStore()
         self.pause_store = PostgreSQLPauseStore(config.dsn)
@@ -273,6 +274,7 @@ class Daemon:
             watchdog_store=self.watchdog,
             watchdog_timeout_sec=self.config.safety_sell.watchdog_timeout_sec,
             killswitch_store=self.killswitch_store,
+            ledger_outbox=self.outbox,  # dcy-018 / REQ-029: estimated-cash overlay
         )
         transport.consume_rpc_forever(
             topology.snapshot_queue(self.config.instance_key), handler, self.stop)