feat: strategy builder

frontend/src/hooks/useApi.ts

@@ -1856,6 +1856,19 @@ export const useOptimizeStrategy = () =>
       api.post<OptimizeResponse>('/strategy-builder/optimize', body).then(r => r.data),
   })
 
+// Day-by-day mark-to-market of a fixed set of legs against REAL accumulated Saxo history
+// between two dates — not a scenario, a replay of what actually happened.
+export type ReplayPoint = { date: string; spot: number | null; position_value: number; pnl: number }
+export type ReplayResult = {
+  symbol: string; saxo_symbol: string; start_date: string; end_date: string
+  entry_date: string; entry_value: number; final_pnl: number
+  points: ReplayPoint[]; missing_dates: string[]
+}
+export const useReplayStrategy = () =>
+  useMutation<ReplayResult, Error, { symbol: string; legs: StrategyLeg[]; start_date: string; end_date: string; contract_size?: number }>({
+    mutationFn: (body) => api.post('/strategy-builder/replay', body).then(r => r.data),
+  })
+
 // Mode 1 of the scenario/profile/constraints split — what Greek behavior the scenario
 // alone already implies, before the user sets any explicit target (project memory:
 // Strategy Builder Greeks plan, Phase 4).