Cumulative REALIZED PnL curve over the last N days

**Metric: REALIZED PnL only** — closed-trade profit via FIFO sell matching; excludes unrealized (mark-to-market) PnL. Walks every fill on the caller org's wallets (filtered by optional `walletId`/`walletAddress`/`provider`), applies the same FIFO sell match used by `/v1/me/pnl`, and returns one cumulative-realized point per sell event within the window. The first and last timestamps of the window are always included so the chart spans the full requested range. `days` is clamped to [1, 30]. Sort/groupBy/cursor are NOT accepted — the curve is implicitly time-ordered. **Choosing the right PnL curve:** this endpoint = REALIZED (FIFO, closed trades). For **TOTAL** PnL incl. unrealized (NAV-based `ΔNAV − Δnet-deposits`, i.e. what the provider's own PnL chart shows) use `/v1/me/wallets/{id}/pnl-curve` (single wallet) or `/v1/portfolio/pnl` (cross-provider merge).