docs(dcy-007): confirm-discovery — daily trade history + realized PnL API

일일 거래내역(GET /trades) + 실현 PnL(GET /pnl/realized) 조회 API.
운영 모니터링 목적으로 issue #11에서 제기된 필요성.
사장님 결정: OQ-1 실현 PnL=weighted average cost(WAC),
OQ-2 전체 portfolio 집계=Out of Scope.
상태 confirmed, Ready for REQ Drafting: true.
M1(6/22) fast-track 대상.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VHtM5Ws1HKCKQ4JGi6GRb5

docs/discovery/index.md

@@ -12,3 +12,4 @@
 | dcy-004_20260520_token-issuance-and-lifecycle-overhaul | 20260520 | 토큰 발급 및 관리 전면 정비 — client token 폐지, service-token rotate 정상화, 발급 권한 매트릭스, 만료·회전·자동 revoke 정책 | [Discovery](./dcy-004_20260520_token-issuance-and-lifecycle-overhaul.md) | confirmed |
 | dcy-005_20260601_rel-001-feedback-cleanup | 20260601 | REL-001 Feedback 정합화 — ledger_trades.asset_id 명명 / session no_expiry enforcement / health db_enabled | [Discovery](./dcy-005_20260601_rel-001-feedback-cleanup.md) | confirmed |
 | dcy-006_20260605_ledger-trade-write-portfolio-state-return | 20260605 | ledger trade write 회계 책임 단일화 — 응답에 portfolio 상태 포함 + portfolio_ledger/ledger_trades 테이블 통합 (issue #8) | [Discovery](./dcy-006_20260605_ledger-trade-write-portfolio-state-return.md) | confirmed |
+| dcy-007_20260616_daily-trade-history-and-realized-pnl-query-api | 20260616 | 일일 거래내역 + 실현 PnL 조회 API (운영 리포트/프론트 데이터 소스, issue #11) | [Discovery](./dcy-007_20260616_daily-trade-history-and-realized-pnl-query-api.md) | confirmed |