Deliver BAT-004: broker execution + KIS adapter + durable handoff

Implement REQ-011~015 (dcy-003): the order-execution layer on top of the
BAT-002 slot-core daemon, connecting intents to real orders.
- application: BrokerPort (submit/poll_fill/cancel) + ExecutionService
  (claim -> submit -> poll -> transition -> rollback -> reconcile)
- adapters/broker: PaperBroker (deterministic async double) and KISBroker
  (KIS Open API: token, order-cash, inquire-daily-ccld, cancel; VTS sandbox
  tr_ids; live account gated behind allow_live)
- persistence: option-A execution queue (find_pending_for_dispatch FOR
  UPDATE SKIP LOCKED, mark_dispatched idempotency guard, clear_dispatch)
- runtime: background execution loop in the daemon lifespan + startup
  reconcile; config selects paper|kis

Verification (real KIS VTS 모의투자 + PostgreSQL): 92 passed, ruff clean,
domain import sweep shows zero broker/web/db deps, buy->holding /
sell->closed / reject->idle, idempotent dispatch (exactly one order),
reconcile after crash creates no duplicate order, KIS sandbox token+submit
round-trip, and a daemon E2E through the background loop. Align the four
baseline docs. BAT-004 -> release-candidate; REQ-011~015 -> Implemented.

KIS live-account go-live, partial-fill accrual, option-B outbox, connection
pooling, and the safety floor remain deferred to follow-up Discoveries.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

trex_core/adapters/persistence/postgresql.py

@@ -170,6 +170,48 @@ class PostgreSQLSlotRepository:
                 row = cur.fetchone()
                 return int(row[0]) if row else 0
 
+    # --- order execution queue (BAT-004 / REQ-013, option A) ---
+    def find_pending_for_dispatch(self) -> Optional[Slot]:
+        with self._psycopg.connect(self._dsn) as conn:
+            with conn.cursor() as cur:
+                cur.execute(
+                    f"SELECT {_SLOT_COLUMNS} FROM daily_slot "
+                    "WHERE status IN ('pending_buy','pending_sell') AND broker_order_id IS NULL "
+                    "ORDER BY updated_at LIMIT 1 FOR UPDATE SKIP LOCKED"
+                )
+                row = cur.fetchone()
+                return self._row_to_slot(row) if row else None
+
+    def mark_dispatched(self, slot_id: UUID, broker_order_id: str) -> bool:
+        with self._psycopg.connect(self._dsn, autocommit=False) as conn:
+            with conn.cursor() as cur:
+                cur.execute(
+                    "UPDATE daily_slot SET broker_order_id=%s, updated_at=%s "
+                    "WHERE slot_id=%s AND broker_order_id IS NULL",
+                    (broker_order_id, datetime.now(tz=timezone.utc), slot_id),
+                )
+                ok = cur.rowcount == 1
+                conn.commit()
+                return ok
+
+    def list_dispatched_pending(self) -> list[Slot]:
+        with self._psycopg.connect(self._dsn) as conn:
+            with conn.cursor() as cur:
+                cur.execute(
+                    f"SELECT {_SLOT_COLUMNS} FROM daily_slot "
+                    "WHERE status IN ('pending_buy','pending_sell') AND broker_order_id IS NOT NULL"
+                )
+                return [self._row_to_slot(r) for r in cur.fetchall()]
+
+    def clear_dispatch(self, slot_id: UUID) -> None:
+        with self._psycopg.connect(self._dsn, autocommit=False) as conn:
+            with conn.cursor() as cur:
+                cur.execute(
+                    "UPDATE daily_slot SET broker_order_id=NULL, updated_at=%s WHERE slot_id=%s",
+                    (datetime.now(tz=timezone.utc), slot_id),
+                )
+                conn.commit()
+
     def count_slots_by_status(self, trading_date: date) -> dict[SlotState, int]:
         with self._psycopg.connect(self._dsn) as conn:
             with conn.cursor() as cur: