feat: courbe PnL historique + VaR dans les cards Dashboard

- Card PnL : area chart historique depuis pnl_snapshots (gradient couleur
  selon PnL positif/négatif, axes date + %, tooltip)
- Card Risque : bloc VaR 95% (Historique / CVaR / Monte Carlo ×1.5)
  depuis le dernier var_snapshot, avec horodatage du calcul

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

frontend/src/pages/Dashboard.tsx

@@ -1,4 +1,5 @@
 import { useMemo, useState } from 'react'
+import { useQuery } from '@tanstack/react-query'
 import {
   useGeoRiskScore, useAllQuotes,
   useCalendar, usePortfolioSummary, useLastScores, useAllPatterns, useMacroRegime,
@@ -11,7 +12,10 @@ import clsx from 'clsx'
 import type { Quote } from '../types'
 import { format } from 'date-fns'
 import { fr } from 'date-fns/locale'
-import { RadarChart, PolarGrid, PolarAngleAxis, Radar, ResponsiveContainer } from 'recharts'
+import {
+  RadarChart, PolarGrid, PolarAngleAxis, Radar, ResponsiveContainer,
+  AreaChart, Area, XAxis, YAxis, Tooltip, CartesianGrid,
+} from 'recharts'
 import { scoreColor } from '../components/TradeIdeas'
 
 const riskGauge = (score: number) => {
@@ -88,6 +92,20 @@ export default function Dashboard() {
   const { data: cycleStatusData } = useCycleStatus()
   const { data: geoNews } = useGeoNews()
 
+  // Historical PnL curve + latest VaR snapshot
+  const { data: pnlHistoryData } = useQuery({
+    queryKey: ['dash-pnl-history'],
+    queryFn: () => fetch('/api/var/pnl/snapshots?limit=200').then(r => r.ok ? r.json() : { snapshots: [] }),
+    staleTime: 120_000,
+    retry: 1,
+  })
+  const { data: latestVarData } = useQuery({
+    queryKey: ['dash-var-latest'],
+    queryFn: () => fetch('/api/var/latest').then(r => r.ok ? r.json() : { snapshot: null }),
+    staleTime: 120_000,
+    retry: 1,
+  })
+
   const [pnlView, setPnlView] = useState<'simulated' | 'portfolio'>(() =>
     (localStorage.getItem('dash_pnl_view') as any) ?? 'simulated'
   )
@@ -400,6 +418,46 @@ export default function Dashboard() {
                   </div>
                 </div>
               )}
+              {/* PnL historical sparkline */}
+              {(() => {
+                const snaps: any[] = [...(pnlHistoryData?.snapshots ?? [])].reverse()
+                if (snaps.length < 2) return null
+                const chartData = snaps.map(s => ({
+                  date: s.snapped_at?.slice(5, 10),
+                  pnl: s.total_pnl_pct ?? 0,
+                }))
+                const minVal = Math.min(...chartData.map(d => d.pnl))
+                const maxVal = Math.max(...chartData.map(d => d.pnl))
+                const isPositive = chartData[chartData.length - 1]?.pnl >= 0
+                const strokeColor = isPositive ? '#34d399' : '#f87171'
+                const gradId = 'pnlGrad'
+                return (
+                  <div className="mt-2 pt-2 border-t border-slate-700/30">
+                    <div className="text-[9px] text-slate-600 mb-1">Courbe PnL historique ({snaps.length} pts)</div>
+                    <ResponsiveContainer width="100%" height={72}>
+                      <AreaChart data={chartData} margin={{ top: 2, right: 0, left: -38, bottom: 0 }}>
+                        <defs>
+                          <linearGradient id={gradId} x1="0" y1="0" x2="0" y2="1">
+                            <stop offset="5%" stopColor={strokeColor} stopOpacity={0.25} />
+                            <stop offset="95%" stopColor={strokeColor} stopOpacity={0} />
+                          </linearGradient>
+                        </defs>
+                        <CartesianGrid strokeDasharray="3 3" stroke="#1e293b" vertical={false} />
+                        <XAxis dataKey="date" tick={{ fontSize: 8, fill: '#475569' }}
+                          interval={Math.max(0, Math.floor(chartData.length / 5) - 1)} />
+                        <YAxis domain={[minVal - 0.1, maxVal + 0.1]} tick={{ fontSize: 8, fill: '#475569' }} unit="%" />
+                        <Tooltip
+                          contentStyle={{ background: '#0f172a', border: '1px solid #334155', borderRadius: 6, fontSize: 10, padding: '4px 8px' }}
+                          labelStyle={{ color: '#64748b' }}
+                          formatter={(v: any) => [`${v >= 0 ? '+' : ''}${Number(v).toFixed(3)}%`, 'PnL']}
+                        />
+                        <Area type="monotone" dataKey="pnl" stroke={strokeColor} strokeWidth={1.5}
+                          fill={`url(#${gradId})`} dot={false} />
+                      </AreaChart>
+                    </ResponsiveContainer>
+                  </div>
+                )
+              })()}
             </Link>
           )
         })()}
@@ -457,6 +515,34 @@ export default function Dashboard() {
                   {openCount > 0 ? `${openCount} positions` : 'Aucune position'}
                 </div>
               )}
+              {/* Latest VaR snapshot */}
+              {(() => {
+                const snap = latestVarData?.snapshot
+                if (!snap) return null
+                const hv = snap.hist_var_1d_pct
+                const cv = snap.hist_cvar_pct
+                const mv = snap.mc_var_1d_pct
+                const ts = snap.computed_at?.slice(0, 16).replace('T', ' ')
+                return (
+                  <div className="mt-2 pt-2 border-t border-slate-700/30">
+                    <div className="text-[9px] text-slate-600 mb-1.5">VaR 95% · {ts} UTC</div>
+                    <div className="grid grid-cols-3 gap-1.5">
+                      {[
+                        { label: 'Hist.', val: hv, color: 'text-blue-400' },
+                        { label: 'CVaR', val: cv, color: 'text-orange-400' },
+                        { label: 'MC×1.5', val: mv, color: 'text-red-400' },
+                      ].map(({ label, val, color }) => (
+                        <div key={label} className="bg-dark-700/60 rounded px-2 py-1.5 text-center">
+                          <div className="text-[8px] text-slate-600 mb-0.5">{label}</div>
+                          <div className={clsx('text-xs font-bold font-mono', color)}>
+                            {val != null ? `${val >= 0 ? '+' : ''}${val.toFixed(2)}%` : '—'}
+                          </div>
+                        </div>
+                      ))}
+                    </div>
+                  </div>
+                )
+              })()}
             </Link>
           )
         })()}