Implement BAT-006: portfolio-hub ledger integration (REQ-017~019)

- REQ-017: LedgerPort contract (application/ledger_port.py) + portfolio-hub
  adapter + in-memory stub (adapters/ledger/), TREX_PORTFOLIO_HUB_* config
- REQ-018: fill→ledger recording in execution loop; FillStatus carries
  execution_id (deterministic synth) + fee; paper/kis adapters updated
- REQ-019: ledger outbox + retry worker (application/ledger_outbox.py),
  correlation_id idempotency, outcome vocabulary; 002_create_ledger_outbox.sql
- Tests: in-memory/portfolio-hub ledger, execution ledger hook, outbox,
  domain import sweep

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

trex_core/adapters/broker/paper.py

@@ -10,7 +10,12 @@ from __future__ import annotations
 import threading
 from typing import Optional
 
-from trex_core.application.broker_port import FillStatus, OrderAck, OrderRequest
+from trex_core.application.broker_port import (
+    FillStatus,
+    OrderAck,
+    OrderRequest,
+    calculate_fee,
+)
 
 
 class _Order:
@@ -72,7 +77,14 @@ class PaperBroker:
             step = self._qty_per_poll if self._qty_per_poll is not None else (o.qty - o.filled)
             o.filled = min(o.qty, o.filled + step)
             if o.filled >= o.qty:
-                return FillStatus(state="filled", filled_qty=o.filled, avg_price=o.price)
+                # Deterministic execution_id (dcy-004 OQ-3):
+                #   paper:{broker_order_id}:{filled_qty}
+                execution_id = f"paper:{o.oid}:{o.filled}"
+                fee = calculate_fee(o.side, o.filled * o.price)
+                return FillStatus(
+                    state="filled", filled_qty=o.filled, avg_price=o.price,
+                    execution_id=execution_id, fee=fee, tax=0.0,
+                )
             return FillStatus(state="partially_filled", filled_qty=o.filled, avg_price=o.price)
 
     def cancel_order(self, broker_order_id: str, *, side: str, symbol: str, qty: int) -> bool: