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>

docs/batches/index.md

@@ -46,3 +46,4 @@
 | BAT-036 | standard | confirmed | REQ-048 (CHG-20260611-01), REQ-005 (CHG-20260611-01) | dcy-024 | [bat-036](./bat-036_20260611_safety-sell-disable-mode/) |
 | BAT-037 | standard | release-candidate | REQ-073 (CHG-20260612-01) | dcy-025 (REQ-073 change-req) | [bat-037](./bat-037_20260612_slots-rpc-available-slots/) |
 | BAT-038 | standard | release-candidate | REQ-018 (CHG-20260612-01) | dcy-026 (issue #24) | [bat-038](./bat-038_20260612_sell-transaction-tax-fee/) |
+| BAT-039 | standard | release-candidate | REQ-011 (CHG-20260612-01) | 없음 (issue #4) | [bat-039](./bat-039_20260612_paper-seq-redis-persistence/) |