feat: add paper trading capital controls — API endpoint + UI with presets, fix status/metrics to read real state, fix migration duplicates

frontend/src/api/hooks.ts

@@ -397,6 +397,15 @@ export function useSetTradingMode() {
   });
 }
 
+export function useSetTradingCapital() {
+  const qc = useQueryClient();
+  return useMutation({
+    mutationFn: (initial_capital: number) =>
+      apiPut<{ initial_capital: number; active_pool: number; reserve_pool: number }>('trading', '/api/trading/capital', { initial_capital }),
+    onSuccess: () => qc.invalidateQueries({ queryKey: ['trading-config'] }),
+  });
+}
+
 export function usePendingApprovals() {
   return useGet<Approval[]>(['pending-approvals'], 'query', '/api/admin/trading/approvals');
 }