fix(paper): BAT-039 — paper order seq Redis 영속화 (재시작 멱등 키 충돌 방지, REQ-011/issue #4)

REQ-011 change-req(CHG-20260612-01)→구현→confirm-req-implemented(CHG-20260612-02)
전체 delivery. paper 한정 결정성 버그(프로덕션 무관).

- seq_store.py 신규: SeqStore 포트 + RedisSeqStore(원자 INCR, 재시작 단조·영속)
  + InMemorySeqStore(폴백/테스트). REQ-016 token_cache 패턴 재사용.
- paper.py: optional seq_store 주입. 미주입 시 기존 in-memory 동작 byte-for-byte 유지.
- config.py/daemon.py: TREX_PAPER_REDIS_URL → RedisSeqStore wiring
  (key=trex:broker:paper:{instance_key}:order-seq).
- 런타임 Redis 오류는 전파(silent in-memory 폴백 금지 — 버그 재현 방지).
- tests: 재시작 단조성/correlation_id 비충돌/in-memory 폴백/fake redis INCR (5).
  434 passed (+5), ruff clean.

REQ-011 Approved→Implemented, BAT-039 release-candidate. issue #4 close.

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

trex_core/runtime/daemon.py

@@ -84,10 +84,19 @@ def _build_broker(config: DaemonConfig) -> BrokerPort:
             base_url=k.base_url, timeout=k.timeout, allow_live=k.allow_live,
             token_cache=token_cache,
         )
+    seq_store = None
+    if config.paper.redis_url:
+        from trex_core.adapters.broker.seq_store import RedisSeqStore
+
+        seq_store = RedisSeqStore(
+            config.paper.redis_url,
+            key=f"trex:broker:paper:{config.instance_key}:order-seq",
+        )
     return PaperBroker(
         fill_after_polls=config.paper.fill_after_polls,
         qty_per_poll=config.paper.qty_per_poll,
         reject_symbols=set(config.paper.reject_symbols),
+        seq_store=seq_store,
     )