feat: trade lifecycle management — close, archive, target/stop alerts

- DB: 9 new columns on trade_entry_prices (status, closed_at, close_reason,
  close_note, pnl_realized, close_price, target_pct, stop_loss_pct, signal_threshold)
  via ALTER TABLE migration; close_trade(), get_closed_trades(),
  update_trade_exit_params() helpers; exit_defaults config key
- Backend: PATCH /trades/{id}/close, PATCH /trades/{id}/exit-params,
  GET/PUT /exit-defaults, GET /closed-trades with win-rate/avg-PnL stats;
  trade-mtm now computes alert_type (target_reached|stop_loss) per trade
- Journal: new "Fermés" tab with closed trades table + stats banner (win rate,
  avg PnL, total PnL, best trade); open trades show Cible/Stop progress bar +
  🎯/🛑 alert badges + 1-click close modal (price, reason, note)
- Config: new "Paramètres de sortie" panel — target_pct, stop_loss_pct,
  signal_reversal_mode, signal_reversal_threshold with live sliders

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/hooks/useApi.ts

@@ -404,10 +404,60 @@ export const useTradeMtm = (days = 30) =>
     queryKey: ['journal-mtm', days],
     queryFn: () => api.get(`/journal/trade-mtm?days=${days}`).then(r => r.data),
     staleTime: 0,
-    refetchInterval: 5 * 60_000,   // re-fetch live prices every 5 minutes
+    refetchInterval: 5 * 60_000,
     refetchIntervalInBackground: false,
   })
 
+export const useClosedTrades = (days = 180) =>
+  useQuery({
+    queryKey: ['journal-closed', days],
+    queryFn: () => api.get(`/journal/closed-trades?days=${days}`).then(r => r.data),
+    staleTime: 30_000,
+  })
+
+export const useExitDefaults = () =>
+  useQuery({
+    queryKey: ['journal-exit-defaults'],
+    queryFn: () => api.get('/journal/exit-defaults').then(r => r.data),
+    staleTime: 60_000,
+  })
+
+export const useCloseTrade = () => {
+  const qc = useQueryClient()
+  return useMutation({
+    mutationFn: ({ id, body }: { id: number; body: {
+      close_price: number; pnl_realized?: number;
+      close_reason: string; close_note: string
+    }}) => api.patch(`/journal/trades/${id}/close`, body).then(r => r.data),
+    onSuccess: () => {
+      qc.invalidateQueries({ queryKey: ['journal-mtm'] })
+      qc.invalidateQueries({ queryKey: ['journal-closed'] })
+      qc.invalidateQueries({ queryKey: ['journal-summary'] })
+    },
+  })
+}
+
+export const useUpdateExitParams = () => {
+  const qc = useQueryClient()
+  return useMutation({
+    mutationFn: ({ id, body }: { id: number; body: {
+      target_pct?: number; stop_loss_pct?: number; signal_threshold?: number
+    }}) => api.patch(`/journal/trades/${id}/exit-params`, body).then(r => r.data),
+    onSuccess: () => qc.invalidateQueries({ queryKey: ['journal-mtm'] }),
+  })
+}
+
+export const useSaveExitDefaults = () => {
+  const qc = useQueryClient()
+  return useMutation({
+    mutationFn: (body: {
+      target_pct?: number; stop_loss_pct?: number;
+      signal_reversal_mode?: string; signal_reversal_threshold?: number
+    }) => api.put('/journal/exit-defaults', body).then(r => r.data),
+    onSuccess: () => qc.invalidateQueries({ queryKey: ['journal-exit-defaults'] }),
+  })
+}
+
 // ── Risk Profiles ─────────────────────────────────────────────────────────────
 
 export const useRiskProfiles = () =>