feat: translate all UI strings to English for international release

Complete French→English translation across all frontend pages and backend
services — every label, button, header, empty state, toast, and nav item
is now in English. Build verified clean (tsc + vite). No i18n library
added; direct string replacement throughout.

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

frontend/src/pages/PositionHistory.tsx

@@ -140,13 +140,13 @@ function DiffView({ diffData }: { diffData: any }) {
             {pd.positions_opened > 0 && (
               <div className="text-center">
                 <div className="text-emerald-400 font-bold text-lg">+{pd.positions_opened}</div>
-                <div className="text-[10px] text-slate-500">ouvertes</div>
+                <div className="text-[10px] text-slate-500">opened</div>
               </div>
             )}
             {pd.positions_closed > 0 && (
               <div className="text-center">
                 <div className="text-red-400 font-bold text-lg">-{pd.positions_closed}</div>
-                <div className="text-[10px] text-slate-500">fermées</div>
+                <div className="text-[10px] text-slate-500">closed</div>
               </div>
             )}
           </div>
@@ -159,7 +159,7 @@ function DiffView({ diffData }: { diffData: any }) {
           <div className="flex items-center gap-2 mb-3">
             <Plus className="w-4 h-4 text-emerald-400" />
             <h3 className="text-sm font-semibold text-emerald-400">
-              Nouvelles positions ({new_positions.length})
+              New positions ({new_positions.length})
             </h3>
           </div>
           <div className="space-y-1.5">
@@ -170,7 +170,7 @@ function DiffView({ diffData }: { diffData: any }) {
                   <span className="text-slate-400 ml-2">{p.strategy}</span>
                 </div>
                 <div className="flex gap-4">
-                  <span className="text-slate-500">Entrée: {p.entry_price?.toFixed(2) ?? '—'}</span>
+                  <span className="text-slate-500">Entry: {p.entry_price?.toFixed(2) ?? '—'}</span>
                   <span className={clsx('font-semibold', (p.pnl_pct ?? 0) >= 0 ? 'text-emerald-400' : 'text-red-400')}>
                     {fmt(p.pnl_pct)}
                   </span>
@@ -187,7 +187,7 @@ function DiffView({ diffData }: { diffData: any }) {
           <div className="flex items-center gap-2 mb-3">
             <Minus className="w-4 h-4 text-red-400" />
             <h3 className="text-sm font-semibold text-red-400">
-              Positions fermées ({closed_positions.length})
+              Closed positions ({closed_positions.length})
             </h3>
           </div>
           <div className="space-y-1.5">
@@ -198,7 +198,7 @@ function DiffView({ diffData }: { diffData: any }) {
                   <span className="text-slate-500 ml-2">{p.strategy}</span>
                 </div>
                 <div className="flex gap-4">
-                  <span className="text-slate-500">Dernière val.: {fmt(p.pnl_pct)}</span>
+                  <span className="text-slate-500">Last val.: {fmt(p.pnl_pct)}</span>
                   <span className={clsx('font-semibold', (p.pnl_pct ?? 0) >= 0 ? 'text-emerald-400' : 'text-red-400')}>
                     {fmtEur(p.pnl_eur)}
                   </span>
@@ -213,7 +213,7 @@ function DiffView({ diffData }: { diffData: any }) {
       {changed_positions.length > 0 && (
         <div className="bg-dark-800 border border-slate-700/40 rounded-xl p-4">
           <h3 className="text-sm font-semibold text-white mb-3">
-            Évolution des positions ({changed_positions.length})
+            Position changes ({changed_positions.length})
           </h3>
           <div className="overflow-x-auto">
             <table className="w-full text-xs">
@@ -265,7 +265,7 @@ function SnapshotDetail({ snapId }: { snapId: number }) {
     staleTime: 300_000,
   })
 
-  if (isLoading) return <div className="text-slate-600 text-sm p-4">Chargement…</div>
+  if (isLoading) return <div className="text-slate-600 text-sm p-4">Loading…</div>
   if (!data) return null
 
   const trades: any[] = data.trades_snapshot ?? []
@@ -277,7 +277,7 @@ function SnapshotDetail({ snapId }: { snapId: number }) {
         <div>
           <h3 className="text-sm font-semibold text-white">{fmtDate(data.snapped_at)} UTC</h3>
           {macro?.dominant && (
-            <span className="text-xs text-slate-500 capitalize">Régime : {macro.dominant}</span>
+            <span className="text-xs text-slate-500 capitalize">Regime: {macro.dominant}</span>
           )}
         </div>
         <div className="flex gap-4 text-xs">
@@ -294,7 +294,7 @@ function SnapshotDetail({ snapId }: { snapId: number }) {
             </span>
           </div>
           <div>
-            <span className="text-slate-500">{data.n_open} ouvertes · {data.n_closed} fermées</span>
+            <span className="text-slate-500">{data.n_open} open · {data.n_closed} closed</span>
           </div>
         </div>
       </div>
@@ -304,9 +304,9 @@ function SnapshotDetail({ snapId }: { snapId: number }) {
           <thead>
             <tr className="text-slate-500 border-b border-slate-700/40">
               <th className="text-left pb-2 font-medium">Ticker</th>
-              <th className="text-left pb-2 font-medium">Stratégie</th>
-              <th className="text-right pb-2 font-medium">Entrée</th>
-              <th className="text-right pb-2 font-medium">Prix actuel</th>
+              <th className="text-left pb-2 font-medium">Strategy</th>
+              <th className="text-right pb-2 font-medium">Entry</th>
+              <th className="text-right pb-2 font-medium">Current price</th>
               <th className="text-right pb-2 font-medium">PnL %</th>
               <th className="text-right pb-2 font-medium">PnL €</th>
             </tr>
@@ -329,7 +329,7 @@ function SnapshotDetail({ snapId }: { snapId: number }) {
           </tbody>
         </table>
       ) : (
-        <div className="text-slate-600 text-sm">Aucune position dans ce snapshot</div>
+        <div className="text-slate-600 text-sm">No positions in this snapshot</div>
       )}
     </div>
   )
@@ -397,11 +397,11 @@ export default function PositionHistory() {
         <div>
           <div className="flex items-center gap-3 mb-1">
             <History className="w-6 h-6 text-violet-400" />
-            <h1 className="text-xl font-bold text-white">Historique des Positions</h1>
+            <h1 className="text-xl font-bold text-white">Position History</h1>
           </div>
           <p className="text-slate-400 text-sm">
-            {snapshots.length} snapshot{snapshots.length !== 1 ? 's' : ''} PnL enregistré{snapshots.length !== 1 ? 's' : ''}
-            {snapshots.length > 0 && ` · de ${fmtDate(snapshots[snapshots.length - 1]?.snapped_at)} à ${fmtDate(snapshots[0]?.snapped_at)}`}
+            {snapshots.length} PnL snapshot{snapshots.length !== 1 ? 's' : ''} recorded
+            {snapshots.length > 0 && ` · from ${fmtDate(snapshots[snapshots.length - 1]?.snapped_at)} to ${fmtDate(snapshots[0]?.snapped_at)}`}
           </p>
         </div>
         <div className="flex gap-2 flex-wrap">
@@ -412,7 +412,7 @@ export default function PositionHistory() {
                 className={clsx('px-3 py-1.5 rounded text-xs font-semibold transition-colors',
                   viewMode === 'detail' ? 'bg-slate-600 text-white' : 'bg-dark-700 text-slate-400 hover:text-white')}
               >
-                Détail
+                Detail
               </button>
               <button
                 onClick={() => setViewMode('diff')}
@@ -428,12 +428,12 @@ export default function PositionHistory() {
               onClick={() => { setSelectedA(null); setSelectedB(null); setViewMode('detail') }}
               className="px-3 py-1.5 rounded text-xs text-slate-500 hover:text-slate-300 bg-dark-700"
             >
-              Effacer sélection
+              Clear selection
             </button>
           )}
           <button onClick={() => refetch()}
             className="flex items-center gap-1 px-3 py-1.5 rounded text-xs bg-dark-700 text-slate-400 hover:text-white">
-            <RefreshCw className="w-3.5 h-3.5" /> Actualiser
+            <RefreshCw className="w-3.5 h-3.5" /> Refresh
           </button>
         </div>
       </div>
@@ -448,24 +448,24 @@ export default function PositionHistory() {
       {/* Selection banner */}
       {(selectedA || selectedB) && (
         <div className="flex items-center gap-3 bg-dark-800 border border-slate-700/40 rounded-xl px-4 py-3 text-xs flex-wrap">
-          <span className="text-slate-500">Sélection diff :</span>
+          <span className="text-slate-500">Diff selection:</span>
           {selectedA ? (
             <span className="flex items-center gap-1.5 bg-blue-900/30 text-blue-400 border border-blue-700/40 px-2.5 py-1 rounded">
               <span className="font-bold">A</span>
               {fmtDate(snapshots.find(s => s.id === selectedA)?.snapped_at ?? '')}
             </span>
-          ) : <span className="text-slate-600">A : non sélectionné</span>}
+          ) : <span className="text-slate-600">A: not selected</span>}
           <ArrowRight className="w-3.5 h-3.5 text-slate-600" />
           {selectedB ? (
             <span className="flex items-center gap-1.5 bg-violet-900/30 text-violet-400 border border-violet-700/40 px-2.5 py-1 rounded">
               <span className="font-bold">B</span>
               {fmtDate(snapshots.find(s => s.id === selectedB)?.snapped_at ?? '')}
             </span>
-          ) : <span className="text-slate-600">B : non sélectionné</span>}
+          ) : <span className="text-slate-600">B: not selected</span>}
           {canDiff && (
             <button onClick={() => setViewMode('diff')}
               className="ml-auto bg-violet-600 hover:bg-violet-500 text-white px-3 py-1 rounded text-xs font-semibold">
-              Voir le diff
+              View diff
             </button>
           )}
         </div>
@@ -475,10 +475,10 @@ export default function PositionHistory() {
       {!isLoading && snapshots.length === 0 && (
         <div className="text-center py-20">
           <History className="w-14 h-14 text-slate-700 mx-auto mb-4" />
-          <div className="text-slate-400 font-semibold mb-2">Aucun snapshot PnL disponible</div>
+          <div className="text-slate-400 font-semibold mb-2">No PnL snapshots available</div>
           <p className="text-slate-600 text-sm max-w-md mx-auto">
-            Activez le Scheduler PnL dans la Configuration ou déclenchez un snapshot manuellement
-            depuis la page Configuration → Auto-Cycle &amp; Logging.
+            Enable the PnL Scheduler in Configuration or trigger a snapshot manually
+            from the Configuration → Auto-Cycle &amp; Logging page.
           </p>
         </div>
       )}
@@ -491,7 +491,7 @@ export default function PositionHistory() {
             {/* Mini sparkline */}
             {sparkData.length > 2 && (
               <div className="bg-dark-800 border border-slate-700/40 rounded-xl p-3">
-                <div className="text-xs text-slate-500 mb-2">PnL portfolio dans le temps</div>
+                <div className="text-xs text-slate-500 mb-2">Portfolio PnL over time</div>
                 <ResponsiveContainer width="100%" height={80}>
                   <LineChart data={sparkData} margin={{ top: 4, right: 4, left: -30, bottom: 0 }}>
                     <XAxis dataKey="date" hide />
@@ -507,7 +507,7 @@ export default function PositionHistory() {
             {/* Snapshot list */}
             <div className="bg-dark-800 border border-slate-700/40 rounded-xl p-3 space-y-1.5 max-h-[calc(100vh-320px)] overflow-y-auto">
               <div className="text-[10px] text-slate-600 uppercase tracking-wider px-1 mb-2">
-                {snapshots.length} snapshots — cliquez pour détail · A/B pour diff
+                {snapshots.length} snapshots — click for detail · A/B to diff
               </div>
               {snapshots.map(s => (
                 <div key={s.id} onClick={() => { setActiveDetail(s.id); setViewMode('detail') }}>
@@ -527,7 +527,7 @@ export default function PositionHistory() {
           <div className="lg:col-span-2">
             {viewMode === 'diff' && canDiff && (
               diffLoading
-                ? <div className="text-slate-500 text-sm p-4">Calcul du diff…</div>
+                ? <div className="text-slate-500 text-sm p-4">Computing diff…</div>
                 : diffError
                 ? <div className="text-red-400 text-sm p-4">{String(diffError)}</div>
                 : diffData ? <DiffView diffData={diffData} />
@@ -542,8 +542,8 @@ export default function PositionHistory() {
               <div className="flex flex-col items-center justify-center py-20 text-center">
                 <TrendingUp className="w-12 h-12 text-slate-700 mb-4" />
                 <div className="text-slate-500 text-sm">
-                  Cliquez sur un snapshot pour voir le détail<br />
-                  ou sélectionnez A et B pour comparer deux valuations
+                  Click a snapshot to see the detail<br />
+                  or select A and B to compare two valuations
                 </div>
               </div>
             )}
@@ -552,7 +552,7 @@ export default function PositionHistory() {
               <div className="flex flex-col items-center justify-center py-20 text-center">
                 <TrendingDown className="w-12 h-12 text-slate-700 mb-4" />
                 <div className="text-slate-500 text-sm">
-                  Sélectionnez deux snapshots (A et B) depuis la liste pour voir le diff
+                  Select two snapshots (A and B) from the list to view the diff
                 </div>
               </div>
             )}