feat(pnl): trade history + realized PnL API (WAC) — BAT-017, REQ-039~042 Implemented

- GET /v1/portfolios/{id}/trades and GET /v1/portfolios/{id}/pnl/realized endpoints
- Weighted Average Cost (WAC) realized PnL calculation in app/domain/pnl.py
- cost_basis and data_completeness_warning returned in pnl API response
- Test coverage: 50 passed (WAC 20 + trades 12 + pnl 18), full 427 passed regression ✓
- WAC validated against 199,300 unit e2e test cases
- DB migration: none required
- QC: qc-reviewer PASS-WITH-NOTES; team lead confirm-batch-verification → release-candidate
- Remaining non-blocking: symbol filter edge case testing, HTTP_422 deprecation

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

app/schemas/v1.py

@@ -2,7 +2,7 @@
 
 from __future__ import annotations
 
-from datetime import datetime
+from datetime import date, datetime
 from decimal import Decimal
 from typing import Any, Literal
 
@@ -249,3 +249,50 @@ class AssetCatalogResponse(BaseModel):
 class AssetCatalogListResponse(BaseModel):
     items: list[AssetCatalogResponse]
     total: int
+
+
+# ---------------------------------------------------------------------------
+# GET /v1/portfolios/{id}/trades (REQ-039)
+# ---------------------------------------------------------------------------
+
+class TradeHistoryItem(BaseModel):
+    ledger_entry_id: int
+    portfolio_id: str
+    order_id: str | None = None
+    execution_id: str | None = None
+    side: str
+    quantity: float
+    price: float
+    fee_amount: float
+    tax_amount: float
+    executed_at: datetime
+    recorded_at: datetime | None = None
+
+
+class TradeHistoryResponse(BaseModel):
+    items: list[TradeHistoryItem]
+    total: int
+
+
+# ---------------------------------------------------------------------------
+# GET /v1/portfolios/{id}/pnl/realized (REQ-040)
+# ---------------------------------------------------------------------------
+
+class RealizedPnlItem(BaseModel):
+    symbol: str | None = None
+    executed_at: datetime | None = None
+    quantity: float
+    sell_price: float
+    cost_basis_per_unit: float
+    fee_amount: float
+    tax_amount: float
+    realized_pnl: float
+    order_id: str | None = None
+    execution_id: str | None = None
+
+
+class RealizedPnlResponse(BaseModel):
+    total_realized_pnl: float
+    items: list[RealizedPnlItem]
+    cost_basis_from: datetime | None = None
+    data_completeness_warning: str | None = None