Add Binance SIM market adapter and exchange switch in settings.

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/src/api/client.ts

@@ -88,6 +88,8 @@ export type MarketSnapshot = {
   connected: boolean;
   updated_at_ms: number | null;
   index_px: number | null;
+  exchange?: string;
+  perp_inst_id?: string;
   pair: {
     expiry_ymd: string;
     strike: number;
@@ -180,5 +182,9 @@ export type StrategySettings = {
   close_bid_mark_max_pct: number;
   perp_qty_eth: number;
   option_qty_eth: number;
+  exchange: "okx" | "binance";
+  perp_inst_id?: string;
+  option_inst_family?: string;
+  index_inst_id?: string;
   ledger: { equity: number; available: number };
 };