docs(batch): draft-batch BAT-029 (dcy-020 BAT-γ) + FR-7 재정의(계약 키=slot_id)

사용자 결정으로 intent 계약 키를 portfolio_id → slot_id 재정의(코어 native·스냅샷
slots[] round-trip·portfolio-hub 식별 누수 방지). 매도는 이미 slot_id; 매수만 이동
(레거시 portfolio_id dual-accept, 폐기 BAT-δ).

- REQ-061 change-req(CHG-20260610-03): 계약 키 slot_id 로 body/AC 재작성
- dcy-020 FR-7 재정의 주석(2026-06-10)
- draft-batch BAT-029(REQ-061/062/063) + design 확정
  (D1=slot_id 계약, D2=reconcile 3자 확장+A=error/B·C=warning)
- batches/index BAT-029 등록

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

docs/batches/index.md

@@ -36,3 +36,4 @@
 | BAT-026 | batch-lite | release-candidate | REQ-048 (CHG-20260609-01), REQ-010 (CHG-20260609-01) | 없음 (trex-orb-v1 정합) | [bat-026](./bat-026_20260609_config-dir-env-and-config-path/) |
 | BAT-027 | standard | planning | REQ-056, REQ-057 | dcy-020 (BAT-α) | [bat-027](./bat-027_20260610_asset-permanent-slot-foundation/) |
 | BAT-028 | standard | planning | REQ-058, REQ-059, REQ-060 | dcy-020 (BAT-β) | [bat-028](./bat-028_20260610_universe-reconcile-and-active-admission/) |
+| BAT-029 | standard | planning | REQ-061, REQ-062, REQ-063 | dcy-020 (BAT-γ) | [bat-029](./bat-029_20260610_asset-keyed-intent-and-divergence/) |